// SPDX-License-Identifier: GPL-2.0-only
/*
 * File:        mca_drv.c
 * Purpose:     Generic MCA handling layer
 *
 * Copyright (C) 2004 FUJITSU LIMITED
 * Copyright (C) 2004 Hidetoshi Seto <seto.hidetoshi@jp.fujitsu.com>
 * Copyright (C) 2005 Silicon Graphics, Inc
 * Copyright (C) 2005 Keith Owens <kaos@sgi.com>
 * Copyright (C) 2006 Russ Anderson <rja@sgi.com>
 */
#include <linux/types.h>
#include <linux/init.h>
#include <linux/sched.h>
#include <linux/interrupt.h>
#include <linux/irq.h>
#include <linux/kallsyms.h>
#include <linux/memblock.h>
#include <linux/acpi.h>
#include <linux/timer.h>
#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/smp.h>
#include <linux/workqueue.h>
#include <linux/mm.h>
#include <linux/slab.h>

#include <asm/delay.h>
#include <asm/machvec.h>
#include <asm/page.h>
#include <asm/ptrace.h>
#include <asm/sal.h>
#include <asm/mca.h>

#include <asm/irq.h>
#include <asm/hw_irq.h>

#include "mca_drv.h"

/* max size of SAL error record (default) */
static int sal_rec_max = 10000;

/* from mca_drv_asm.S */
extern void *mca_handler_bhhook(void);

static DEFINE_SPINLOCK(mca_bh_lock);

typedef enum {
        MCA_IS_LOCAL  = 0,
        MCA_IS_GLOBAL = 1
} mca_type_t;

#define MAX_PAGE_ISOLATE 1024

static struct page *page_isolate[MAX_PAGE_ISOLATE];
static int num_page_isolate = 0;

typedef enum {
        ISOLATE_NG,
        ISOLATE_OK,
        ISOLATE_NONE
} isolate_status_t;

typedef enum {
        MCA_NOT_RECOVERED = 0,
        MCA_RECOVERED     = 1
} recovery_status_t;

/*
 *  This pool keeps pointers to the section part of SAL error record
 */
static struct {
        slidx_list_t *buffer; /* section pointer list pool */
        int          cur_idx; /* Current index of section pointer list pool */
        int          max_idx; /* Maximum index of section pointer list pool */
} slidx_pool;

static int
fatal_mca(const char *fmt, ...)
{
        va_list args;
        char buf[256];

        va_start(args, fmt);
        vsnprintf(buf, sizeof(buf), fmt, args);
        va_end(args);
        ia64_mca_printk(KERN_ALERT "MCA: %s\n", buf);

        return MCA_NOT_RECOVERED;
}

static int
mca_recovered(const char *fmt, ...)
{
        va_list args;
        char buf[256];

        va_start(args, fmt);
        vsnprintf(buf, sizeof(buf), fmt, args);
        va_end(args);
        ia64_mca_printk(KERN_INFO "MCA: %s\n", buf);

        return MCA_RECOVERED;
}

/**
 * mca_page_isolate - isolate a poisoned page in order not to use it later
 * @paddr:      poisoned memory location
 *
 * Return value:
 *      one of isolate_status_t, ISOLATE_OK/NG/NONE.
 */

static isolate_status_t
mca_page_isolate(unsigned long paddr)
{
        int i;
        struct page *p;

        /* whether physical address is valid or not */
        if (!ia64_phys_addr_valid(paddr))
                return ISOLATE_NONE;

        if (!pfn_valid(paddr >> PAGE_SHIFT))
                return ISOLATE_NONE;

        /* convert physical address to physical page number */
        p = pfn_to_page(paddr>>PAGE_SHIFT);

        /* check whether a page number have been already registered or not */
        for (i = 0; i < num_page_isolate; i++)
                if (page_isolate[i] == p)
                        return ISOLATE_OK; /* already listed */

        /* limitation check */
        if (num_page_isolate == MAX_PAGE_ISOLATE)
                return ISOLATE_NG;

        /* kick pages having attribute 'SLAB' or 'Reserved' */
        if (PageSlab(p) || PageReserved(p))
                return ISOLATE_NG;

        /* add attribute 'Reserved' and register the page */
        get_page(p);
        SetPageReserved(p);
        page_isolate[num_page_isolate++] = p;

        return ISOLATE_OK;
}

/**
 * mca_hanlder_bh - Kill the process which occurred memory read error
 * @paddr:      poisoned address received from MCA Handler
 */

void
mca_handler_bh(unsigned long paddr, void *iip, unsigned long ipsr)
{
        ia64_mlogbuf_dump();
        printk(KERN_ERR "OS_MCA: process [cpu %d, pid: %d, uid: %d, "
                "iip: %p, psr: 0x%lx,paddr: 0x%lx](%s) encounters MCA.\n",
               raw_smp_processor_id(), current->pid,
                from_kuid(&init_user_ns, current_uid()),
                iip, ipsr, paddr, current->comm);

        spin_lock(&mca_bh_lock);
        switch (mca_page_isolate(paddr)) {
        case ISOLATE_OK:
                printk(KERN_DEBUG "Page isolation: ( %lx ) success.\n", paddr);
                break;
        case ISOLATE_NG:
                printk(KERN_CRIT "Page isolation: ( %lx ) failure.\n", paddr);
                break;
        default:
                break;
        }
        spin_unlock(&mca_bh_lock);

        /* This process is about to be killed itself */
        do_exit(SIGKILL);
}

/**
 * mca_make_peidx - Make index of processor error section
 * @slpi:       pointer to record of processor error section
 * @peidx:      pointer to index of processor error section
 */

static void
mca_make_peidx(sal_log_processor_info_t *slpi, peidx_table_t *peidx)
{
        /*
         * calculate the start address of
         *   "struct cpuid_info" and "sal_processor_static_info_t".
         */
        u64 total_check_num = slpi->valid.num_cache_check
                                + slpi->valid.num_tlb_check
                                + slpi->valid.num_bus_check
                                + slpi->valid.num_reg_file_check
                                + slpi->valid.num_ms_check;
        u64 head_size = sizeof(sal_log_mod_error_info_t) * total_check_num
                        + sizeof(sal_log_processor_info_t);
        u64 mid_size  = slpi->valid.cpuid_info * sizeof(struct sal_cpuid_info);

        peidx_head(peidx)   = slpi;
        peidx_mid(peidx)    = (struct sal_cpuid_info *)
                (slpi->valid.cpuid_info ? ((char*)slpi + head_size) : NULL);
        peidx_bottom(peidx) = (sal_processor_static_info_t *)
                (slpi->valid.psi_static_struct ?
                        ((char*)slpi + head_size + mid_size) : NULL);
}

/**
 * mca_make_slidx -  Make index of SAL error record
 * @buffer:     pointer to SAL error record
 * @slidx:      pointer to index of SAL error record
 *
 * Return value:
 *      1 if record has platform error / 0 if not
 */
#define LOG_INDEX_ADD_SECT_PTR(sect, ptr) \
        {slidx_list_t *hl = &slidx_pool.buffer[slidx_pool.cur_idx]; \
        hl->hdr = ptr; \
        list_add(&hl->list, &(sect)); \
        slidx_pool.cur_idx = (slidx_pool.cur_idx + 1)%slidx_pool.max_idx; }

static int
mca_make_slidx(void *buffer, slidx_table_t *slidx)
{
        int platform_err = 0;
        int record_len = ((sal_log_record_header_t*)buffer)->len;
        u32 ercd_pos;
        int sects;
        sal_log_section_hdr_t *sp;

        /*
         * Initialize index referring current record
         */
        INIT_LIST_HEAD(&(slidx->proc_err));
        INIT_LIST_HEAD(&(slidx->mem_dev_err));
        INIT_LIST_HEAD(&(slidx->sel_dev_err));
        INIT_LIST_HEAD(&(slidx->pci_bus_err));
        INIT_LIST_HEAD(&(slidx->smbios_dev_err));
        INIT_LIST_HEAD(&(slidx->pci_comp_err));
        INIT_LIST_HEAD(&(slidx->plat_specific_err));
        INIT_LIST_HEAD(&(slidx->host_ctlr_err));
        INIT_LIST_HEAD(&(slidx->plat_bus_err));
        INIT_LIST_HEAD(&(slidx->unsupported));

        /*
         * Extract a Record Header
         */
        slidx->header = buffer;

        /*
         * Extract each section records
         * (arranged from "int ia64_log_platform_info_print()")
         */
        for (ercd_pos = sizeof(sal_log_record_header_t), sects = 0;
                ercd_pos < record_len; ercd_pos += sp->len, sects++) {
                sp = (sal_log_section_hdr_t *)((char*)buffer + ercd_pos);
                if (!efi_guidcmp(sp->guid, SAL_PROC_DEV_ERR_SECT_GUID)) {
                        LOG_INDEX_ADD_SECT_PTR(slidx->proc_err, sp);
                } else if (!efi_guidcmp(sp->guid,
                                SAL_PLAT_MEM_DEV_ERR_SECT_GUID)) {
                        platform_err = 1;
                        LOG_INDEX_ADD_SECT_PTR(slidx->mem_dev_err, sp);
                } else if (!efi_guidcmp(sp->guid,
                                SAL_PLAT_SEL_DEV_ERR_SECT_GUID)) {
                        platform_err = 1;
                        LOG_INDEX_ADD_SECT_PTR(slidx->sel_dev_err, sp);
                } else if (!efi_guidcmp(sp->guid,
                                SAL_PLAT_PCI_BUS_ERR_SECT_GUID)) {
                        platform_err = 1;
                        LOG_INDEX_ADD_SECT_PTR(slidx->pci_bus_err, sp);
                } else if (!efi_guidcmp(sp->guid,
                                SAL_PLAT_SMBIOS_DEV_ERR_SECT_GUID)) {
                        platform_err = 1;
                        LOG_INDEX_ADD_SECT_PTR(slidx->smbios_dev_err, sp);
                } else if (!efi_guidcmp(sp->guid,
                                SAL_PLAT_PCI_COMP_ERR_SECT_GUID)) {
                        platform_err = 1;
                        LOG_INDEX_ADD_SECT_PTR(slidx->pci_comp_err, sp);
                } else if (!efi_guidcmp(sp->guid,
                                SAL_PLAT_SPECIFIC_ERR_SECT_GUID)) {
                        platform_err = 1;
                        LOG_INDEX_ADD_SECT_PTR(slidx->plat_specific_err, sp);
                } else if (!efi_guidcmp(sp->guid,
                                SAL_PLAT_HOST_CTLR_ERR_SECT_GUID)) {
                        platform_err = 1;
                        LOG_INDEX_ADD_SECT_PTR(slidx->host_ctlr_err, sp);
                } else if (!efi_guidcmp(sp->guid,
                                SAL_PLAT_BUS_ERR_SECT_GUID)) {
                        platform_err = 1;
                        LOG_INDEX_ADD_SECT_PTR(slidx->plat_bus_err, sp);
                } else {
                        LOG_INDEX_ADD_SECT_PTR(slidx->unsupported, sp);
                }
        }
        slidx->n_sections = sects;

        return platform_err;
}

/**
 * init_record_index_pools - Initialize pool of lists for SAL record index
 *
 * Return value:
 *      0 on Success / -ENOMEM on Failure
 */
static int
init_record_index_pools(void)
{
        int i;
        int rec_max_size;  /* Maximum size of SAL error records */
        int sect_min_size; /* Minimum size of SAL error sections */
        /* minimum size table of each section */
        static int sal_log_sect_min_sizes[] = {
                sizeof(sal_log_processor_info_t)
                + sizeof(sal_processor_static_info_t),
                sizeof(sal_log_mem_dev_err_info_t),
                sizeof(sal_log_sel_dev_err_info_t),
                sizeof(sal_log_pci_bus_err_info_t),
                sizeof(sal_log_smbios_dev_err_info_t),
                sizeof(sal_log_pci_comp_err_info_t),
                sizeof(sal_log_plat_specific_err_info_t),
                sizeof(sal_log_host_ctlr_err_info_t),
                sizeof(sal_log_plat_bus_err_info_t),
        };

        /*
         * MCA handler cannot allocate new memory on flight,
         * so we preallocate enough memory to handle a SAL record.
         *
         * Initialize a handling set of slidx_pool:
         *   1. Pick up the max size of SAL error records
         *   2. Pick up the min size of SAL error sections
         *   3. Allocate the pool as enough to 2 SAL records
         *     (now we can estimate the maxinum of section in a record.)
         */

        /* - 1 - */
        rec_max_size = sal_rec_max;

        /* - 2 - */
        sect_min_size = sal_log_sect_min_sizes[0];
        for (i = 1; i < sizeof sal_log_sect_min_sizes/sizeof(size_t); i++)
                if (sect_min_size > sal_log_sect_min_sizes[i])
                        sect_min_size = sal_log_sect_min_sizes[i];

        /* - 3 - */
        slidx_pool.max_idx = (rec_max_size/sect_min_size) * 2 + 1;
        slidx_pool.buffer =
                kmalloc_array(slidx_pool.max_idx, sizeof(slidx_list_t),
                              GFP_KERNEL);

        return slidx_pool.buffer ? 0 : -ENOMEM;
}


/*****************************************************************************
 * Recovery functions                                                        *
 *****************************************************************************/

/**
 * is_mca_global - Check whether this MCA is global or not
 * @peidx:      pointer of index of processor error section
 * @pbci:       pointer to pal_bus_check_info_t
 * @sos:        pointer to hand off struct between SAL and OS
 *
 * Return value:
 *      MCA_IS_LOCAL / MCA_IS_GLOBAL
 */

static mca_type_t
is_mca_global(peidx_table_t *peidx, pal_bus_check_info_t *pbci,
              struct ia64_sal_os_state *sos)
{
        pal_processor_state_info_t *psp =
                (pal_processor_state_info_t*)peidx_psp(peidx);

        /*
         * PAL can request a rendezvous, if the MCA has a global scope.
         * If "rz_always" flag is set, SAL requests MCA rendezvous
         * in spite of global MCA.
         * Therefore it is local MCA when rendezvous has not been requested.
         * Failed to rendezvous, the system must be down.
         */
        switch (sos->rv_rc) {
                case -1: /* SAL rendezvous unsuccessful */
                        return MCA_IS_GLOBAL;
                case  0: /* SAL rendezvous not required */
                        return MCA_IS_LOCAL;
                case  1: /* SAL rendezvous successful int */
                case  2: /* SAL rendezvous successful int with init */
                default:
                        break;
        }

        /*
         * If One or more Cache/TLB/Reg_File/Uarch_Check is here,
         * it would be a local MCA. (i.e. processor internal error)
         */
        if (psp->tc || psp->cc || psp->rc || psp->uc)
                return MCA_IS_LOCAL;
        
        /*
         * Bus_Check structure with Bus_Check.ib (internal bus error) flag set
         * would be a global MCA. (e.g. a system bus address parity error)
         */
        if (!pbci || pbci->ib)
                return MCA_IS_GLOBAL;

        /*
         * Bus_Check structure with Bus_Check.eb (external bus error) flag set
         * could be either a local MCA or a global MCA.
         *
         * Referring Bus_Check.bsi:
         *   0: Unknown/unclassified
         *   1: BERR#
         *   2: BINIT#
         *   3: Hard Fail
         * (FIXME: Are these SGI specific or generic bsi values?)
         */
        if (pbci->eb)
                switch (pbci->bsi) {
                        case 0:
                                /* e.g. a load from poisoned memory */
                                return MCA_IS_LOCAL;
                        case 1:
                        case 2:
                        case 3:
                                return MCA_IS_GLOBAL;
                }

        return MCA_IS_GLOBAL;
}

/**
 * get_target_identifier - Get the valid Cache or Bus check target identifier.
 * @peidx:      pointer of index of processor error section
 *
 * Return value:
 *      target address on Success / 0 on Failure
 */
static u64
get_target_identifier(peidx_table_t *peidx)
{
        u64 target_address = 0;
        sal_log_mod_error_info_t *smei;
        pal_cache_check_info_t *pcci;
        int i, level = 9;

        /*
         * Look through the cache checks for a valid target identifier
         * If more than one valid target identifier, return the one
         * with the lowest cache level.
         */
        for (i = 0; i < peidx_cache_check_num(peidx); i++) {
                smei = (sal_log_mod_error_info_t *)peidx_cache_check(peidx, i);
                if (smei->valid.target_identifier && smei->target_identifier) {
                        pcci = (pal_cache_check_info_t *)&(smei->check_info);
                        if (!target_address || (pcci->level < level)) {
                                target_address = smei->target_identifier;
                                level = pcci->level;
                                continue;
                        }
                }
        }
        if (target_address)
                return target_address;

        /*
         * Look at the bus check for a valid target identifier
         */
        smei = peidx_bus_check(peidx, 0);
        if (smei && smei->valid.target_identifier)
                return smei->target_identifier;

        return 0;
}

/**
 * recover_from_read_error - Try to recover the errors which type are "read"s.
 * @slidx:      pointer of index of SAL error record
 * @peidx:      pointer of index of processor error section
 * @pbci:       pointer of pal_bus_check_info
 * @sos:        pointer to hand off struct between SAL and OS
 *
 * Return value:
 *      1 on Success / 0 on Failure
 */

static int
recover_from_read_error(slidx_table_t *slidx,
                        peidx_table_t *peidx, pal_bus_check_info_t *pbci,
                        struct ia64_sal_os_state *sos)
{
        u64 target_identifier;
        pal_min_state_area_t *pmsa;
        struct ia64_psr *psr1, *psr2;
        ia64_fptr_t *mca_hdlr_bh = (ia64_fptr_t*)mca_handler_bhhook;

        /* Is target address valid? */
        target_identifier = get_target_identifier(peidx);
        if (!target_identifier)
                return fatal_mca("target address not valid");

        /*
         * cpu read or memory-mapped io read
         *
         *    offending process  affected process  OS MCA do
         *     kernel mode        kernel mode       down system
         *     kernel mode        user   mode       kill the process
         *     user   mode        kernel mode       down system (*)
         *     user   mode        user   mode       kill the process
         *
         * (*) You could terminate offending user-mode process
         *    if (pbci->pv && pbci->pl != 0) *and* if you sure
         *    the process not have any locks of kernel.
         */

        /* Is minstate valid? */
        if (!peidx_bottom(peidx) || !(peidx_bottom(peidx)->valid.minstate))
                return fatal_mca("minstate not valid");
        psr1 =(struct ia64_psr *)&(peidx_minstate_area(peidx)->pmsa_ipsr);
        psr2 =(struct ia64_psr *)&(peidx_minstate_area(peidx)->pmsa_xpsr);

        /*
         *  Check the privilege level of interrupted context.
         *   If it is user-mode, then terminate affected process.
         */

        pmsa = sos->pal_min_state;
        if (psr1->cpl != 0 ||
           ((psr2->cpl != 0) && mca_recover_range(pmsa->pmsa_iip))) {
                /*
                 *  setup for resume to bottom half of MCA,
                 * "mca_handler_bhhook"
                 */
                /* pass to bhhook as argument (gr8, ...) */
                pmsa->pmsa_gr[8-1] = target_identifier;
                pmsa->pmsa_gr[9-1] = pmsa->pmsa_iip;
                pmsa->pmsa_gr[10-1] = pmsa->pmsa_ipsr;
                /* set interrupted return address (but no use) */
                pmsa->pmsa_br0 = pmsa->pmsa_iip;
                /* change resume address to bottom half */
                pmsa->pmsa_iip = mca_hdlr_bh->fp;
                pmsa->pmsa_gr[1-1] = mca_hdlr_bh->gp;
                /* set cpl with kernel mode */
                psr2 = (struct ia64_psr *)&pmsa->pmsa_ipsr;
                psr2->cpl = 0;
                psr2->ri  = 0;
                psr2->bn  = 1;
                psr2->i  = 0;

                return mca_recovered("user memory corruption. "
                                "kill affected process - recovered.");
        }

        return fatal_mca("kernel context not recovered, iip 0x%lx\n",
                         pmsa->pmsa_iip);
}

/**
 * recover_from_platform_error - Recover from platform error.
 * @slidx:      pointer of index of SAL error record
 * @peidx:      pointer of index of processor error section
 * @pbci:       pointer of pal_bus_check_info
 * @sos:        pointer to hand off struct between SAL and OS
 *
 * Return value:
 *      1 on Success / 0 on Failure
 */

static int
recover_from_platform_error(slidx_table_t *slidx, peidx_table_t *peidx,
                            pal_bus_check_info_t *pbci,
                            struct ia64_sal_os_state *sos)
{
        int status = 0;
        pal_processor_state_info_t *psp =
                (pal_processor_state_info_t*)peidx_psp(peidx);

        if (psp->bc && pbci->eb && pbci->bsi == 0) {
                switch(pbci->type) {
                case 1: /* partial read */
                case 3: /* full line(cpu) read */
                case 9: /* I/O space read */
                        status = recover_from_read_error(slidx, peidx, pbci,
                                                         sos);
                        break;
                case 0: /* unknown */
                case 2: /* partial write */
                case 4: /* full line write */
                case 5: /* implicit or explicit write-back operation */
                case 6: /* snoop probe */
                case 7: /* incoming or outgoing ptc.g */
                case 8: /* write coalescing transactions */
                case 10: /* I/O space write */
                case 11: /* inter-processor interrupt message(IPI) */
                case 12: /* interrupt acknowledge or
                                external task priority cycle */
                default:
                        break;
                }
        } else if (psp->cc && !psp->bc) {       /* Cache error */
                status = recover_from_read_error(slidx, peidx, pbci, sos);
        }

        return status;
}

/*
 * recover_from_tlb_check
 * @peidx:      pointer of index of processor error section
 *
 * Return value:
 *      1 on Success / 0 on Failure
 */
static int
recover_from_tlb_check(peidx_table_t *peidx)
{
        sal_log_mod_error_info_t *smei;
        pal_tlb_check_info_t *ptci;

        smei = (sal_log_mod_error_info_t *)peidx_tlb_check(peidx, 0);
        ptci = (pal_tlb_check_info_t *)&(smei->check_info);

        /*
         * Look for signature of a duplicate TLB DTC entry, which is
         * a SW bug and always fatal.
         */
        if (ptci->op == PAL_TLB_CHECK_OP_PURGE
            && !(ptci->itr || ptci->dtc || ptci->itc))
                return fatal_mca("Duplicate TLB entry");

        return mca_recovered("TLB check recovered");
}

/**
 * recover_from_processor_error
 * @platform:   whether there are some platform error section or not
 * @slidx:      pointer of index of SAL error record
 * @peidx:      pointer of index of processor error section
 * @pbci:       pointer of pal_bus_check_info
 * @sos:        pointer to hand off struct between SAL and OS
 *
 * Return value:
 *      1 on Success / 0 on Failure
 */

static int
recover_from_processor_error(int platform, slidx_table_t *slidx,
                             peidx_table_t *peidx, pal_bus_check_info_t *pbci,
                             struct ia64_sal_os_state *sos)
{
        pal_processor_state_info_t *psp =
                (pal_processor_state_info_t*)peidx_psp(peidx);

        /*
         * Processor recovery status must key off of the PAL recovery
         * status in the Processor State Parameter.
         */

        /*
         * The machine check is corrected.
         */
        if (psp->cm == 1)
                return mca_recovered("machine check is already corrected.");

        /*
         * The error was not contained.  Software must be reset.
         */
        if (psp->us || psp->ci == 0)
                return fatal_mca("error not contained");

        /*
         * Look for recoverable TLB check
         */
        if (psp->tc && !(psp->cc || psp->bc || psp->rc || psp->uc))
                return recover_from_tlb_check(peidx);

        /*
         * The cache check and bus check bits have four possible states
         *   cc bc
         *    1  1      Memory error, attempt recovery
         *    1  0      Cache error, attempt recovery
         *    0  1      I/O error, attempt recovery
         *    0  0      Other error type, not recovered
         */
        if (psp->cc == 0 && (psp->bc == 0 || pbci == NULL))
                return fatal_mca("No cache or bus check");

        /*
         * Cannot handle more than one bus check.
         */
        if (peidx_bus_check_num(peidx) > 1)
                return fatal_mca("Too many bus checks");

        if (pbci->ib)
                return fatal_mca("Internal Bus error");
        if (pbci->eb && pbci->bsi > 0)
                return fatal_mca("External bus check fatal status");

        /*
         * This is a local MCA and estimated as a recoverable error.
         */
        if (platform)
                return recover_from_platform_error(slidx, peidx, pbci, sos);

        /*
         * On account of strange SAL error record, we cannot recover.
         */
        return fatal_mca("Strange SAL record");
}

/**
 * mca_try_to_recover - Try to recover from MCA
 * @rec:        pointer to a SAL error record
 * @sos:        pointer to hand off struct between SAL and OS
 *
 * Return value:
 *      1 on Success / 0 on Failure
 */

static int
mca_try_to_recover(void *rec, struct ia64_sal_os_state *sos)
{
        int platform_err;
        int n_proc_err;
        slidx_table_t slidx;
        peidx_table_t peidx;
        pal_bus_check_info_t pbci;

        /* Make index of SAL error record */
        platform_err = mca_make_slidx(rec, &slidx);

        /* Count processor error sections */
        n_proc_err = slidx_count(&slidx, proc_err);

         /* Now, OS can recover when there is one processor error section */
        if (n_proc_err > 1)
                return fatal_mca("Too Many Errors");
        else if (n_proc_err == 0)
                /* Weird SAL record ... We can't do anything */
                return fatal_mca("Weird SAL record");

        /* Make index of processor error section */
        mca_make_peidx((sal_log_processor_info_t*)
                slidx_first_entry(&slidx.proc_err)->hdr, &peidx);

        /* Extract Processor BUS_CHECK[0] */
        *((u64*)&pbci) = peidx_check_info(&peidx, bus_check, 0);

        /* Check whether MCA is global or not */
        if (is_mca_global(&peidx, &pbci, sos))
                return fatal_mca("global MCA");
        
        /* Try to recover a processor error */
        return recover_from_processor_error(platform_err, &slidx, &peidx,
                                            &pbci, sos);
}

/*
 * =============================================================================
 */

int __init mca_external_handler_init(void)
{
        if (init_record_index_pools())
                return -ENOMEM;

        /* register external mca handlers */
        if (ia64_reg_MCA_extension(mca_try_to_recover)) {       
                printk(KERN_ERR "ia64_reg_MCA_extension failed.\n");
                kfree(slidx_pool.buffer);
                return -EFAULT;
        }
        return 0;
}

void __exit mca_external_handler_exit(void)
{
        /* unregister external mca handlers */
        ia64_unreg_MCA_extension();
        kfree(slidx_pool.buffer);
}

module_init(mca_external_handler_init);
module_exit(mca_external_handler_exit);

module_param(sal_rec_max, int, 0644);
MODULE_PARM_DESC(sal_rec_max, "Max size of SAL error record");

MODULE_DESCRIPTION("ia64 platform dependent mca handler driver");
MODULE_LICENSE("GPL");