Merge tag 'trace-printf-v6.13' of git://git.kernel.org/pub/scm/linux/kernel/git/trace...

[drm/drm-misc.git] / arch / powerpc / kernel / fadump.c

// 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 <linux/debugfs.h>
#include <linux/of.h>
#include <linux/of_fdt.h>

#include <asm/page.h>
#include <asm/fadump.h>
#include <asm/fadump-internal.h>
#include <asm/setup.h>
#include <asm/interrupt.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);

#ifndef CONFIG_PRESERVE_FA_DUMP

static struct kobject *fadump_kobj;

static atomic_t cpus_in_fadump;
static DEFINE_MUTEX(fadump_mutex);

#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];
static 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 remaining portion of fadump reserved memory will be not given
 * to CMA and pages for those 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.
 */
void __init fadump_cma_init(void)
{
        unsigned long long base, size, end;
        int rc;

        if (!fw_dump.fadump_supported || !fw_dump.fadump_enabled ||
                        fw_dump.dump_active)
                return;
        /*
         * Do not use CMA if user has provided fadump=nocma kernel parameter.
         */
        if (fw_dump.nocma || !fw_dump.boot_memory_size)
                return;

        /*
         * [base, end) should be reserved during early init in
         * fadump_reserve_mem(). No need to check this here as
         * cma_init_reserved_mem() already checks for overlap.
         * Here we give the aligned chunk of this reserved memory to CMA.
         */
        base = fw_dump.reserve_dump_area_start;
        size = fw_dump.boot_memory_size;
        end = base + size;

        base = ALIGN(base, CMA_MIN_ALIGNMENT_BYTES);
        end = ALIGN_DOWN(end, CMA_MIN_ALIGNMENT_BYTES);
        size = end - base;

        if (end <= base) {
                pr_warn("%s: Too less memory to give to CMA\n", __func__);
                return;
        }

        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;
        }

        /*
         *  If CMA activation fails, keep the pages reserved, instead of
         *  exposing them to buddy allocator. Same as 'fadump=nocma' case.
         */
        cma_reserve_pages_on_error(fadump_cma);

        /*
         * So we now have successfully initialized cma area for fadump.
         */
        pr_info("Initialized [0x%llx, %luMB] cma area from [0x%lx, %luMB] "
                "bytes of memory reserved for firmware-assisted dump\n",
                cma_get_base(fadump_cma), cma_get_size(fadump_cma) >> 20,
                fw_dump.reserve_dump_area_start,
                fw_dump.boot_memory_size >> 20);
        return;
}
#endif /* CONFIG_CMA */

/*
 * Additional parameters meant for capture kernel are placed in a dedicated area.
 * If this is capture kernel boot, append these parameters to bootargs.
 */
void __init fadump_append_bootargs(void)
{
        char *append_args;
        size_t len;

        if (!fw_dump.dump_active || !fw_dump.param_area_supported || !fw_dump.param_area)
                return;

        if (fw_dump.param_area < fw_dump.boot_mem_top) {
                if (memblock_reserve(fw_dump.param_area, COMMAND_LINE_SIZE)) {
                        pr_warn("WARNING: Can't use additional parameters area!\n");
                        fw_dump.param_area = 0;
                        return;
                }
        }

        append_args = (char *)fw_dump.param_area;
        len = strlen(boot_command_line);

        /*
         * Too late to fail even if cmdline size exceeds. Truncate additional parameters
         * to cmdline size and proceed anyway.
         */
        if (len + strlen(append_args) >= COMMAND_LINE_SIZE - 1)
                pr_warn("WARNING: Appending parameters exceeds cmdline size. Truncating!\n");

        pr_debug("Cmdline: %s\n", boot_command_line);
        snprintf(boot_command_line + len, COMMAND_LINE_SIZE - len, " %s", append_args);
        pr_info("Updated cmdline: %s\n", boot_command_line);
}

/* 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 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 __init 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, NULL, NULL);
        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 __init get_fadump_area_size(void)
{
        unsigned long size = 0;

        size += fw_dump.cpu_state_data_size;
        size += fw_dump.hpte_region_size;
        /*
         * Account for pagesize alignment of boot memory area destination address.
         * This faciliates in mmap reading of first kernel's memory.
         */
        size = PAGE_ALIGN(size);
        size += fw_dump.boot_memory_size;
        size += sizeof(struct fadump_crash_info_header);

        /* 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 max_boot_mem_rgns = fw_dump.ops->fadump_max_boot_mem_rgns();
        int i = fw_dump.boot_mem_regs_cnt++;

        if (fw_dump.boot_mem_regs_cnt > max_boot_mem_rgns) {
                fw_dump.boot_mem_regs_cnt = max_boot_mem_rgns;
                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 __init 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());

                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;
                }
        }

        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));
        }

        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 its 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->cpu_mask = *cpu_online_mask;

        /*
         * If we came in via system reset, wait a while for the secondary
         * CPUs to enter.
         */
        if (TRAP(&(fdh->regs)) == INTERRUPT_SYSTEM_RESET) {
                msecs = CRASH_TIMEOUT;
                while ((atomic_read(&cpus_in_fadump) < ncpus) && (--msecs > 0))
                        mdelay(1);
        }

        fw_dump.ops->fadump_trigger(fdh, str);
}

u32 *__init 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_regs(&prstatus.pr_reg, regs);
        buf = append_elf_note(buf, CRASH_CORE_NOTE_NAME, NT_PRSTATUS,
                              &prstatus, sizeof(prstatus));
        return buf;
}

void __init 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 *__init 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 __init 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_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 (IS_ENABLED(CONFIG_PPC64_ELF_ABI_V2))
                elf->e_flags = 2;
        else if (IS_ENABLED(CONFIG_PPC64_ELF_ABI_V1))
                elf->e_flags = 1;
        else
                elf->e_flags = 0;

        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;
}

/*
 * 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 void __init populate_elf_pt_load(struct elf_phdr *phdr, u64 start,
                             u64 size, unsigned long long offset)
{
        phdr->p_align   = 0;
        phdr->p_memsz   = size;
        phdr->p_filesz  = size;
        phdr->p_paddr   = start;
        phdr->p_offset  = offset;
        phdr->p_type    = PT_LOAD;
        phdr->p_flags   = PF_R|PF_W|PF_X;
        phdr->p_vaddr   = (unsigned long)__va(start);
}

static void __init fadump_populate_elfcorehdr(struct fadump_crash_info_header *fdh)
{
        char *bufp;
        struct elfhdr *elf;
        struct elf_phdr *phdr;
        u64 boot_mem_dest_offset;
        unsigned long long i, ra_start, ra_end, ra_size, mstart, mend;

        bufp = (char *) fw_dump.elfcorehdr_addr;
        fadump_init_elfcore_header(bufp);
        elf = (struct elfhdr *)bufp;
        bufp += sizeof(struct elfhdr);

        /*
         * Set up ELF PT_NOTE, a placeholder for CPU notes information.
         * The notes info will be populated later by platform-specific code.
         * 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;
        /* Increment number of program headers. */
        (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   = phdr->p_offset = fdh->vmcoreinfo_raddr;
        phdr->p_memsz   = phdr->p_filesz = fdh->vmcoreinfo_size;
        /* Increment number of program headers. */
        (elf->e_phnum)++;

        /*
         * Setup PT_LOAD sections. first include boot memory regions
         * and then add rest of the memory regions.
         */
        boot_mem_dest_offset = fw_dump.boot_mem_dest_addr;
        for (i = 0; i < fw_dump.boot_mem_regs_cnt; i++) {
                phdr = (struct elf_phdr *)bufp;
                bufp += sizeof(struct elf_phdr);
                populate_elf_pt_load(phdr, fw_dump.boot_mem_addr[i],
                                     fw_dump.boot_mem_sz[i],
                                     boot_mem_dest_offset);
                /* Increment number of program headers. */
                (elf->e_phnum)++;
                boot_mem_dest_offset += fw_dump.boot_mem_sz[i];
        }

        /* Memory reserved for fadump in first kernel */
        ra_start = fw_dump.reserve_dump_area_start;
        ra_size = get_fadump_area_size();
        ra_end = ra_start + ra_size;

        phdr = (struct elf_phdr *)bufp;
        for_each_mem_range(i, &mstart, &mend) {
                /* Boot memory regions already added, skip them now */
                if (mstart < fw_dump.boot_mem_top) {
                        if (mend > fw_dump.boot_mem_top)
                                mstart = fw_dump.boot_mem_top;
                        else
                                continue;
                }

                /* Handle memblock regions overlaps with fadump reserved area */
                if ((ra_start < mend) && (ra_end > mstart)) {
                        if ((mstart < ra_start) && (mend > ra_end)) {
                                populate_elf_pt_load(phdr, mstart, ra_start - mstart, mstart);
                                /* Increment number of program headers. */
                                (elf->e_phnum)++;
                                bufp += sizeof(struct elf_phdr);
                                phdr = (struct elf_phdr *)bufp;
                                populate_elf_pt_load(phdr, ra_end, mend - ra_end, ra_end);
                        } else if (mstart < ra_start) {
                                populate_elf_pt_load(phdr, mstart, ra_start - mstart, mstart);
                        } else if (ra_end < mend) {
                                populate_elf_pt_load(phdr, ra_end, mend - ra_end, ra_end);
                        }
                } else {
                /* No overlap with fadump reserved memory region */
                        populate_elf_pt_load(phdr, mstart, mend - mstart, mstart);
                }

                /* Increment number of program headers. */
                (elf->e_phnum)++;
                bufp += sizeof(struct elf_phdr);
                phdr = (struct elf_phdr *) bufp;
        }
}

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->version = FADUMP_HEADER_VERSION;
        /* We will set the crashing cpu id in crash_fadump() during crash. */
        fdh->crashing_cpu = FADUMP_CPU_UNKNOWN;

        /*
         * The physical address and size of vmcoreinfo are required in the
         * second kernel to prepare elfcorehdr.
         */
        fdh->vmcoreinfo_raddr = fadump_relocate(paddr_vmcoreinfo_note());
        fdh->vmcoreinfo_size = VMCOREINFO_NOTE_SIZE;


        fdh->pt_regs_sz = sizeof(struct pt_regs);
        /*
         * When LPAR is terminated by PYHP, ensure all possible CPUs'
         * register data is processed while exporting the vmcore.
         */
        fdh->cpu_mask = *cpu_possible_mask;
        fdh->cpu_mask_sz = sizeof(struct cpumask);

        return addr;
}

static int register_fadump(void)
{
        unsigned long addr;

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

        addr = fw_dump.fadumphdr_addr;

        /* Initialize fadump crash info header. */
        addr = init_fadump_header(addr);

        /* 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);
        }

        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;
        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)
                        swap(mem_ranges[idx], mem_ranges[i]);
        }

        /* 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_free_elfcorehdr_buf(void)
{
        if (fw_dump.elfcorehdr_addr == 0 || fw_dump.elfcorehdr_size == 0)
                return;

        /*
         * Before freeing the memory of `elfcorehdr`, reset the global
         * `elfcorehdr_addr` to prevent modules like `vmcore` from accessing
         * invalid memory.
         */
        elfcorehdr_addr = ELFCORE_ADDR_ERR;
        fadump_free_buffer(fw_dump.elfcorehdr_addr, fw_dump.elfcorehdr_size);
        fw_dump.elfcorehdr_addr = 0;
        fw_dump.elfcorehdr_size = 0;
}

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_free_elfcorehdr_buf();
        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 __init 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);
}

/*
 * /sys/kernel/fadump/hotplug_ready sysfs node returns 1, which inidcates
 * to usersapce that fadump re-registration is not required on memory
 * hotplug events.
 */
static ssize_t hotplug_ready_show(struct kobject *kobj,
                                      struct kobj_attribute *attr,
                                      char *buf)
{
        return sprintf(buf, "%d\n", 1);
}

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 bootargs_append_show(struct kobject *kobj,
                                   struct kobj_attribute *attr,
                                   char *buf)
{
        return sprintf(buf, "%s\n", (char *)__va(fw_dump.param_area));
}

static ssize_t bootargs_append_store(struct kobject *kobj,
                                   struct kobj_attribute *attr,
                                   const char *buf, size_t count)
{
        char *params;

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

        if (count >= COMMAND_LINE_SIZE)
                return -EINVAL;

        /*
         * Fail here instead of handling this scenario with
         * some silly workaround in capture kernel.
         */
        if (saved_command_line_len + count >= COMMAND_LINE_SIZE) {
                pr_err("Appending parameters exceeds cmdline size!\n");
                return -ENOSPC;
        }

        params = __va(fw_dump.param_area);
        strscpy_pad(params, buf, COMMAND_LINE_SIZE);
        /* Remove newline character at the end. */
        if (params[count-1] == '\n')
                params[count-1] = '\0';

        return count;
}

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 kobj_attribute hotplug_ready_attr = __ATTR_RO(hotplug_ready);
static struct kobj_attribute bootargs_append_attr = __ATTR_RW(bootargs_append);

static struct attribute *fadump_attrs[] = {
        &enable_attr.attr,
        &register_attr.attr,
        &mem_reserved_attr.attr,
        &hotplug_ready_attr.attr,
        NULL,
};

ATTRIBUTE_GROUPS(fadump);

DEFINE_SHOW_ATTRIBUTE(fadump_region);

static void __init 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;
        }

        if (fw_dump.param_area) {
                rc = sysfs_create_file(fadump_kobj, &bootargs_append_attr.attr);
                if (rc)
                        pr_err("unable to create bootargs_append sysfs file (%d)\n", rc);
        }

        debugfs_create_file("fadump_region", 0444, arch_debugfs_dir, 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;
}

static int __init fadump_setup_elfcorehdr_buf(void)
{
        int elf_phdr_cnt;
        unsigned long elfcorehdr_size;

        /*
         * Program header for CPU notes comes first, followed by one for
         * vmcoreinfo, and the remaining program headers correspond to
         * memory regions.
         */
        elf_phdr_cnt = 2 + fw_dump.boot_mem_regs_cnt + memblock_num_regions(memory);
        elfcorehdr_size = sizeof(struct elfhdr) + (elf_phdr_cnt * sizeof(struct elf_phdr));
        elfcorehdr_size = PAGE_ALIGN(elfcorehdr_size);

        fw_dump.elfcorehdr_addr = (u64)fadump_alloc_buffer(elfcorehdr_size);
        if (!fw_dump.elfcorehdr_addr) {
                pr_err("Failed to allocate %lu bytes for elfcorehdr\n",
                       elfcorehdr_size);
                return -ENOMEM;
        }
        fw_dump.elfcorehdr_size = elfcorehdr_size;
        return 0;
}

/*
 * Check if the fadump header of crashed kernel is compatible with fadump kernel.
 *
 * It checks the magic number, endianness, and size of non-primitive type
 * members of fadump header to ensure safe dump collection.
 */
static bool __init is_fadump_header_compatible(struct fadump_crash_info_header *fdh)
{
        if (fdh->magic_number == FADUMP_CRASH_INFO_MAGIC_OLD) {
                pr_err("Old magic number, can't process the dump.\n");
                return false;
        }

        if (fdh->magic_number != FADUMP_CRASH_INFO_MAGIC) {
                if (fdh->magic_number == swab64(FADUMP_CRASH_INFO_MAGIC))
                        pr_err("Endianness mismatch between the crashed and fadump kernels.\n");
                else
                        pr_err("Fadump header is corrupted.\n");

                return false;
        }

        /*
         * Dump collection is not safe if the size of non-primitive type members
         * of the fadump header do not match between crashed and fadump kernel.
         */
        if (fdh->pt_regs_sz != sizeof(struct pt_regs) ||
            fdh->cpu_mask_sz != sizeof(struct cpumask)) {
                pr_err("Fadump header size mismatch.\n");
                return false;
        }

        return true;
}

static void __init fadump_process(void)
{
        struct fadump_crash_info_header *fdh;

        fdh = (struct fadump_crash_info_header *) __va(fw_dump.fadumphdr_addr);
        if (!fdh) {
                pr_err("Crash info header is empty.\n");
                goto err_out;
        }

        /* Avoid processing the dump if fadump header isn't compatible */
        if (!is_fadump_header_compatible(fdh))
                goto err_out;

        /* Allocate buffer for elfcorehdr */
        if (fadump_setup_elfcorehdr_buf())
                goto err_out;

        fadump_populate_elfcorehdr(fdh);

        /* Let platform update the CPU notes in elfcorehdr */
        if (fw_dump.ops->fadump_process(&fw_dump) < 0)
                goto err_out;

        /*
         * elfcorehdr is now ready to be exported.
         *
         * set elfcorehdr_addr so that vmcore module will export the
         * elfcorehdr through '/proc/vmcore'.
         */
        elfcorehdr_addr = virt_to_phys((void *)fw_dump.elfcorehdr_addr);
        return;

err_out:
        fadump_invalidate_release_mem();
}

/*
 * Reserve memory to store additional parameters to be passed
 * for fadump/capture kernel.
 */
void __init fadump_setup_param_area(void)
{
        phys_addr_t range_start, range_end;

        if (!fw_dump.param_area_supported || fw_dump.dump_active)
                return;

        /* This memory can't be used by PFW or bootloader as it is shared across kernels */
        if (early_radix_enabled()) {
                /*
                 * Anywhere in the upper half should be good enough as all memory
                 * is accessible in real mode.
                 */
                range_start = memblock_end_of_DRAM() / 2;
                range_end = memblock_end_of_DRAM();
        } else {
                /*
                 * Passing additional parameters is supported for hash MMU only
                 * if the first memory block size is 768MB or higher.
                 */
                if (ppc64_rma_size < 0x30000000)
                        return;

                /*
                 * 640 MB to 768 MB is not used by PFW/bootloader. So, try reserving
                 * memory for passing additional parameters in this range to avoid
                 * being stomped on by PFW/bootloader.
                 */
                range_start = 0x2A000000;
                range_end = range_start + 0x4000000;
        }

        fw_dump.param_area = memblock_phys_alloc_range(COMMAND_LINE_SIZE,
                                                       COMMAND_LINE_SIZE,
                                                       range_start,
                                                       range_end);
        if (!fw_dump.param_area) {
                pr_warn("WARNING: Could not setup area to pass additional parameters!\n");
                return;
        }

        memset((void *)fw_dump.param_area, 0, COMMAND_LINE_SIZE);
}

/*
 * 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) {
                fadump_process();
        }
        /* Initialize the kernel dump memory structure and register with f/w */
        else if (fw_dump.reserve_dump_area_size) {
                fw_dump.ops->fadump_init_mem_struct(&fw_dump);
                register_fadump();
        }

        /*
         * 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;
}
/*
 * Use subsys_initcall_sync() here because there is dependency with
 * crash_save_vmcoreinfo_init(), which must run first to ensure vmcoreinfo initialization
 * is done before registering with f/w.
 */
subsys_initcall_sync(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);
        }
}