// SPDX-License-Identifier: GPL-2.0-or-later
/*
 * FRU (Field-Replaceable Unit) Memory Poison Manager
 *
 * Copyright (c) 2024, Advanced Micro Devices, Inc.
 * All Rights Reserved.
 *
 * Authors:
 *      Naveen Krishna Chatradhi <naveenkrishna.chatradhi@amd.com>
 *      Muralidhara M K <muralidhara.mk@amd.com>
 *      Yazen Ghannam <Yazen.Ghannam@amd.com>
 *
 * Implementation notes, assumptions, and limitations:
 *
 * - FRU memory poison section and memory poison descriptor definitions are not yet
 *   included in the UEFI specification. So they are defined here. Afterwards, they
 *   may be moved to linux/cper.h, if appropriate.
 *
 * - Platforms based on AMD MI300 systems will be the first to use these structures.
 *   There are a number of assumptions made here that will need to be generalized
 *   to support other platforms.
 *
 *   AMD MI300-based platform(s) assumptions:
 *   - Memory errors are reported through x86 MCA.
 *   - The entire DRAM row containing a memory error should be retired.
 *   - There will be (1) FRU memory poison section per CPER.
 *   - The FRU will be the CPU package (processor socket).
 *   - The default number of memory poison descriptor entries should be (8).
 *   - The platform will use ACPI ERST for persistent storage.
 *   - All FRU records should be saved to persistent storage. Module init will
 *     fail if any FRU record is not successfully written.
 *
 * - Boot time memory retirement may occur later than ideal due to dependencies
 *   on other libraries and drivers. This leaves a gap where bad memory may be
 *   accessed during early boot stages.
 *
 * - Enough memory should be pre-allocated for each FRU record to be able to hold
 *   the expected number of descriptor entries. This, mostly empty, record is
 *   written to storage during init time. Subsequent writes to the same record
 *   should allow the Platform to update the stored record in-place. Otherwise,
 *   if the record is extended, then the Platform may need to perform costly memory
 *   management operations on the storage. For example, the Platform may spend time
 *   in Firmware copying and invalidating memory on a relatively slow SPI ROM.
 */

#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

#include <linux/cper.h>
#include <linux/ras.h>
#include <linux/cpu.h>

#include <acpi/apei.h>

#include <asm/cpu_device_id.h>
#include <asm/mce.h>

#include "../debugfs.h"

#include "atl/internal.h"

#define INVALID_CPU                     UINT_MAX

/* Validation Bits */
#define FMP_VALID_ARCH_TYPE             BIT_ULL(0)
#define FMP_VALID_ARCH                  BIT_ULL(1)
#define FMP_VALID_ID_TYPE               BIT_ULL(2)
#define FMP_VALID_ID                    BIT_ULL(3)
#define FMP_VALID_LIST_ENTRIES          BIT_ULL(4)
#define FMP_VALID_LIST                  BIT_ULL(5)

/* FRU Architecture Types */
#define FMP_ARCH_TYPE_X86_CPUID_1_EAX   0

/* FRU ID Types */
#define FMP_ID_TYPE_X86_PPIN            0

/* FRU Memory Poison Section */
struct cper_sec_fru_mem_poison {
        u32 checksum;
        u64 validation_bits;
        u32 fru_arch_type;
        u64 fru_arch;
        u32 fru_id_type;
        u64 fru_id;
        u32 nr_entries;
} __packed;

/* FRU Descriptor ID Types */
#define FPD_HW_ID_TYPE_MCA_IPID         0

/* FRU Descriptor Address Types */
#define FPD_ADDR_TYPE_MCA_ADDR          0

/* Memory Poison Descriptor */
struct cper_fru_poison_desc {
        u64 timestamp;
        u32 hw_id_type;
        u64 hw_id;
        u32 addr_type;
        u64 addr;
} __packed;

/* Collection of headers and sections for easy pointer use. */
struct fru_rec {
        struct cper_record_header       hdr;
        struct cper_section_descriptor  sec_desc;
        struct cper_sec_fru_mem_poison  fmp;
        struct cper_fru_poison_desc     entries[];
} __packed;

/*
 * Pointers to the complete CPER record of each FRU.
 *
 * Memory allocation will include padded space for descriptor entries.
 */
static struct fru_rec **fru_records;

/* system physical addresses array */
static u64 *spa_entries;

static struct dentry *fmpm_dfs_dir;
static struct dentry *fmpm_dfs_entries;

#define CPER_CREATOR_FMP                                                \
        GUID_INIT(0xcd5c2993, 0xf4b2, 0x41b2, 0xb5, 0xd4, 0xf9, 0xc3,   \
                  0xa0, 0x33, 0x08, 0x75)

#define CPER_SECTION_TYPE_FMP                                           \
        GUID_INIT(0x5e4706c1, 0x5356, 0x48c6, 0x93, 0x0b, 0x52, 0xf2,   \
                  0x12, 0x0a, 0x44, 0x58)

/**
 * DOC: max_nr_entries (byte)
 * Maximum number of descriptor entries possible for each FRU.
 *
 * Values between '1' and '255' are valid.
 * No input or '0' will default to FMPM_DEFAULT_MAX_NR_ENTRIES.
 */
static u8 max_nr_entries;
module_param(max_nr_entries, byte, 0644);
MODULE_PARM_DESC(max_nr_entries,
                 "Maximum number of memory poison descriptor entries per FRU");

#define FMPM_DEFAULT_MAX_NR_ENTRIES     8

/* Maximum number of FRUs in the system. */
#define FMPM_MAX_NR_FRU                 256
static unsigned int max_nr_fru;

/* Total length of record including headers and list of descriptor entries. */
static size_t max_rec_len;

#define FMPM_MAX_REC_LEN (sizeof(struct fru_rec) + (sizeof(struct cper_fru_poison_desc) * 255))

/* Total number of SPA entries across all FRUs. */
static unsigned int spa_nr_entries;

/*
 * Protect the local records cache in fru_records and prevent concurrent
 * writes to storage. This is only needed after init once notifier block
 * registration is done.
 *
 * The majority of a record is fixed at module init and will not change
 * during run time. The entries within a record will be updated as new
 * errors are reported. The mutex should be held whenever the entries are
 * accessed during run time.
 */
static DEFINE_MUTEX(fmpm_update_mutex);

#define for_each_fru(i, rec) \
        for (i = 0; rec = fru_records[i], i < max_nr_fru; i++)

static inline u32 get_fmp_len(struct fru_rec *rec)
{
        return rec->sec_desc.section_length - sizeof(struct cper_section_descriptor);
}

static struct fru_rec *get_fru_record(u64 fru_id)
{
        struct fru_rec *rec;
        unsigned int i;

        for_each_fru(i, rec) {
                if (rec->fmp.fru_id == fru_id)
                        return rec;
        }

        pr_debug("Record not found for FRU 0x%016llx\n", fru_id);

        return NULL;
}

/*
 * Sum up all bytes within the FRU Memory Poison Section including the Memory
 * Poison Descriptor entries.
 *
 * Don't include the old checksum here. It's a u32 value, so summing each of its
 * bytes will give the wrong total.
 */
static u32 do_fmp_checksum(struct cper_sec_fru_mem_poison *fmp, u32 len)
{
        u32 checksum = 0;
        u8 *buf, *end;

        /* Skip old checksum. */
        buf = (u8 *)fmp + sizeof(u32);
        end = buf + len;

        while (buf < end)
                checksum += (u8)(*(buf++));

        return checksum;
}

static int update_record_on_storage(struct fru_rec *rec)
{
        u32 len, checksum;
        int ret;

        /* Calculate a new checksum. */
        len = get_fmp_len(rec);

        /* Get the current total. */
        checksum = do_fmp_checksum(&rec->fmp, len);

        /* Use the complement value. */
        rec->fmp.checksum = -checksum;

        pr_debug("Writing to storage\n");

        ret = erst_write(&rec->hdr);
        if (ret) {
                pr_warn("Storage update failed for FRU 0x%016llx\n", rec->fmp.fru_id);

                if (ret == -ENOSPC)
                        pr_warn("Not enough space on storage\n");
        }

        return ret;
}

static bool rec_has_valid_entries(struct fru_rec *rec)
{
        if (!(rec->fmp.validation_bits & FMP_VALID_LIST_ENTRIES))
                return false;

        if (!(rec->fmp.validation_bits & FMP_VALID_LIST))
                return false;

        return true;
}

/*
 * Row retirement is done on MI300 systems, and some bits are 'don't
 * care' for comparing addresses with unique physical rows.  This
 * includes all column bits and the row[13] bit.
 */
#define MASK_ADDR(addr) ((addr) & ~(MI300_UMC_MCA_ROW13 | MI300_UMC_MCA_COL))

static bool fpds_equal(struct cper_fru_poison_desc *old, struct cper_fru_poison_desc *new)
{
        /*
         * Ignore timestamp field.
         * The same physical error may be reported multiple times due to stuck bits, etc.
         *
         * Also, order the checks from most->least likely to fail to shortcut the code.
         */
        if (MASK_ADDR(old->addr) != MASK_ADDR(new->addr))
                return false;

        if (old->hw_id != new->hw_id)
                return false;

        if (old->addr_type != new->addr_type)
                return false;

        if (old->hw_id_type != new->hw_id_type)
                return false;

        return true;
}

static bool rec_has_fpd(struct fru_rec *rec, struct cper_fru_poison_desc *fpd)
{
        unsigned int i;

        for (i = 0; i < rec->fmp.nr_entries; i++) {
                struct cper_fru_poison_desc *fpd_i = &rec->entries[i];

                if (fpds_equal(fpd_i, fpd)) {
                        pr_debug("Found duplicate record\n");
                        return true;
                }
        }

        return false;
}

static void save_spa(struct fru_rec *rec, unsigned int entry,
                     u64 addr, u64 id, unsigned int cpu)
{
        unsigned int i, fru_idx, spa_entry;
        struct atl_err a_err;
        unsigned long spa;

        if (entry >= max_nr_entries) {
                pr_warn_once("FRU descriptor entry %d out-of-bounds (max: %d)\n",
                             entry, max_nr_entries);
                return;
        }

        /* spa_nr_entries is always multiple of max_nr_entries */
        for (i = 0; i < spa_nr_entries; i += max_nr_entries) {
                fru_idx = i / max_nr_entries;
                if (fru_records[fru_idx] == rec)
                        break;
        }

        if (i >= spa_nr_entries) {
                pr_warn_once("FRU record %d not found\n", i);
                return;
        }

        spa_entry = i + entry;
        if (spa_entry >= spa_nr_entries) {
                pr_warn_once("spa_entries[] index out-of-bounds\n");
                return;
        }

        memset(&a_err, 0, sizeof(struct atl_err));

        a_err.addr = addr;
        a_err.ipid = id;
        a_err.cpu  = cpu;

        spa = amd_convert_umc_mca_addr_to_sys_addr(&a_err);
        if (IS_ERR_VALUE(spa)) {
                pr_debug("Failed to get system address\n");
                return;
        }

        spa_entries[spa_entry] = spa;
        pr_debug("fru_idx: %u, entry: %u, spa_entry: %u, spa: 0x%016llx\n",
                 fru_idx, entry, spa_entry, spa_entries[spa_entry]);
}

static void update_fru_record(struct fru_rec *rec, struct mce *m)
{
        struct cper_sec_fru_mem_poison *fmp = &rec->fmp;
        struct cper_fru_poison_desc fpd, *fpd_dest;
        u32 entry = 0;

        mutex_lock(&fmpm_update_mutex);

        memset(&fpd, 0, sizeof(struct cper_fru_poison_desc));

        fpd.timestamp   = m->time;
        fpd.hw_id_type = FPD_HW_ID_TYPE_MCA_IPID;
        fpd.hw_id       = m->ipid;
        fpd.addr_type   = FPD_ADDR_TYPE_MCA_ADDR;
        fpd.addr        = m->addr;

        /* This is the first entry, so just save it. */
        if (!rec_has_valid_entries(rec))
                goto save_fpd;

        /* Ignore already recorded errors. */
        if (rec_has_fpd(rec, &fpd))
                goto out_unlock;

        if (rec->fmp.nr_entries >= max_nr_entries) {
                pr_warn("Exceeded number of entries for FRU 0x%016llx\n", rec->fmp.fru_id);
                goto out_unlock;
        }

        entry  = fmp->nr_entries;

save_fpd:
        save_spa(rec, entry, m->addr, m->ipid, m->extcpu);
        fpd_dest  = &rec->entries[entry];
        memcpy(fpd_dest, &fpd, sizeof(struct cper_fru_poison_desc));

        fmp->nr_entries          = entry + 1;
        fmp->validation_bits    |= FMP_VALID_LIST_ENTRIES;
        fmp->validation_bits    |= FMP_VALID_LIST;

        pr_debug("Updated FRU 0x%016llx entry #%u\n", fmp->fru_id, entry);

        update_record_on_storage(rec);

out_unlock:
        mutex_unlock(&fmpm_update_mutex);
}

static void retire_dram_row(u64 addr, u64 id, u32 cpu)
{
        struct atl_err a_err;

        memset(&a_err, 0, sizeof(struct atl_err));

        a_err.addr = addr;
        a_err.ipid = id;
        a_err.cpu  = cpu;

        amd_retire_dram_row(&a_err);
}

static int fru_handle_mem_poison(struct notifier_block *nb, unsigned long val, void *data)
{
        struct mce *m = (struct mce *)data;
        struct fru_rec *rec;

        if (!mce_is_memory_error(m))
                return NOTIFY_DONE;

        retire_dram_row(m->addr, m->ipid, m->extcpu);

        /*
         * An invalid FRU ID should not happen on real errors. But it
         * could happen from software error injection, etc.
         */
        rec = get_fru_record(m->ppin);
        if (!rec)
                return NOTIFY_DONE;

        update_fru_record(rec, m);

        return NOTIFY_OK;
}

static struct notifier_block fru_mem_poison_nb = {
        .notifier_call  = fru_handle_mem_poison,
        .priority       = MCE_PRIO_LOWEST,
};

static void retire_mem_fmp(struct fru_rec *rec)
{
        struct cper_sec_fru_mem_poison *fmp = &rec->fmp;
        unsigned int i, cpu;

        for (i = 0; i < fmp->nr_entries; i++) {
                struct cper_fru_poison_desc *fpd = &rec->entries[i];
                unsigned int err_cpu = INVALID_CPU;

                if (fpd->hw_id_type != FPD_HW_ID_TYPE_MCA_IPID)
                        continue;

                if (fpd->addr_type != FPD_ADDR_TYPE_MCA_ADDR)
                        continue;

                cpus_read_lock();
                for_each_online_cpu(cpu) {
                        if (topology_ppin(cpu) == fmp->fru_id) {
                                err_cpu = cpu;
                                break;
                        }
                }
                cpus_read_unlock();

                if (err_cpu == INVALID_CPU)
                        continue;

                retire_dram_row(fpd->addr, fpd->hw_id, err_cpu);
                save_spa(rec, i, fpd->addr, fpd->hw_id, err_cpu);
        }
}

static void retire_mem_records(void)
{
        struct fru_rec *rec;
        unsigned int i;

        for_each_fru(i, rec) {
                if (!rec_has_valid_entries(rec))
                        continue;

                retire_mem_fmp(rec);
        }
}

/* Set the CPER Record Header and CPER Section Descriptor fields. */
static void set_rec_fields(struct fru_rec *rec)
{
        struct cper_section_descriptor  *sec_desc = &rec->sec_desc;
        struct cper_record_header       *hdr      = &rec->hdr;

        /*
         * This is a saved record created with fewer max_nr_entries.
         * Update the record lengths and keep everything else as-is.
         */
        if (hdr->record_length && hdr->record_length < max_rec_len) {
                pr_debug("Growing record 0x%016llx from %u to %zu bytes\n",
                         hdr->record_id, hdr->record_length, max_rec_len);
                goto update_lengths;
        }

        memcpy(hdr->signature, CPER_SIG_RECORD, CPER_SIG_SIZE);
        hdr->revision                   = CPER_RECORD_REV;
        hdr->signature_end              = CPER_SIG_END;

        /*
         * Currently, it is assumed that there is one FRU Memory Poison
         * section per CPER. But this may change for other implementations.
         */
        hdr->section_count              = 1;

        /* The logged errors are recoverable. Otherwise, they'd never make it here. */
        hdr->error_severity             = CPER_SEV_RECOVERABLE;

        hdr->validation_bits            = 0;
        hdr->creator_id                 = CPER_CREATOR_FMP;
        hdr->notification_type          = CPER_NOTIFY_MCE;
        hdr->record_id                  = cper_next_record_id();
        hdr->flags                      = CPER_HW_ERROR_FLAGS_PREVERR;

        sec_desc->section_offset        = sizeof(struct cper_record_header);
        sec_desc->revision              = CPER_SEC_REV;
        sec_desc->validation_bits       = 0;
        sec_desc->flags                 = CPER_SEC_PRIMARY;
        sec_desc->section_type          = CPER_SECTION_TYPE_FMP;
        sec_desc->section_severity      = CPER_SEV_RECOVERABLE;

update_lengths:
        hdr->record_length              = max_rec_len;
        sec_desc->section_length        = max_rec_len - sizeof(struct cper_record_header);
}

static int save_new_records(void)
{
        DECLARE_BITMAP(new_records, FMPM_MAX_NR_FRU);
        struct fru_rec *rec;
        unsigned int i;
        int ret = 0;

        for_each_fru(i, rec) {
                /* No need to update saved records that match the current record size. */
                if (rec->hdr.record_length == max_rec_len)
                        continue;

                if (!rec->hdr.record_length)
                        set_bit(i, new_records);

                set_rec_fields(rec);

                ret = update_record_on_storage(rec);
                if (ret)
                        goto out_clear;
        }

        return ret;

out_clear:
        for_each_fru(i, rec) {
                if (!test_bit(i, new_records))
                        continue;

                erst_clear(rec->hdr.record_id);
        }

        return ret;
}

/* Check that the record matches expected types for the current system.*/
static bool fmp_is_usable(struct fru_rec *rec)
{
        struct cper_sec_fru_mem_poison *fmp = &rec->fmp;
        u64 cpuid;

        pr_debug("Validation bits: 0x%016llx\n", fmp->validation_bits);

        if (!(fmp->validation_bits & FMP_VALID_ARCH_TYPE)) {
                pr_debug("Arch type unknown\n");
                return false;
        }

        if (fmp->fru_arch_type != FMP_ARCH_TYPE_X86_CPUID_1_EAX) {
                pr_debug("Arch type not 'x86 Family/Model/Stepping'\n");
                return false;
        }

        if (!(fmp->validation_bits & FMP_VALID_ARCH)) {
                pr_debug("Arch value unknown\n");
                return false;
        }

        cpuid = cpuid_eax(1);
        if (fmp->fru_arch != cpuid) {
                pr_debug("Arch value mismatch: record = 0x%016llx, system = 0x%016llx\n",
                         fmp->fru_arch, cpuid);
                return false;
        }

        if (!(fmp->validation_bits & FMP_VALID_ID_TYPE)) {
                pr_debug("FRU ID type unknown\n");
                return false;
        }

        if (fmp->fru_id_type != FMP_ID_TYPE_X86_PPIN) {
                pr_debug("FRU ID type is not 'x86 PPIN'\n");
                return false;
        }

        if (!(fmp->validation_bits & FMP_VALID_ID)) {
                pr_debug("FRU ID value unknown\n");
                return false;
        }

        return true;
}

static bool fmp_is_valid(struct fru_rec *rec)
{
        struct cper_sec_fru_mem_poison *fmp = &rec->fmp;
        u32 checksum, len;

        len = get_fmp_len(rec);
        if (len < sizeof(struct cper_sec_fru_mem_poison)) {
                pr_debug("fmp length is too small\n");
                return false;
        }

        /* Checksum must sum to zero for the entire section. */
        checksum = do_fmp_checksum(fmp, len) + fmp->checksum;
        if (checksum) {
                pr_debug("fmp checksum failed: sum = 0x%x\n", checksum);
                print_hex_dump_debug("fmp record: ", DUMP_PREFIX_NONE, 16, 1, fmp, len, false);
                return false;
        }

        if (!fmp_is_usable(rec))
                return false;

        return true;
}

static struct fru_rec *get_valid_record(struct fru_rec *old)
{
        struct fru_rec *new;

        if (!fmp_is_valid(old)) {
                pr_debug("Ignoring invalid record\n");
                return NULL;
        }

        new = get_fru_record(old->fmp.fru_id);
        if (!new)
                pr_debug("Ignoring record for absent FRU\n");

        return new;
}

/*
 * Fetch saved records from persistent storage.
 *
 * For each found record:
 * - If it was not created by this module, then ignore it.
 * - If it is valid, then copy its data to the local cache.
 * - If it is not valid, then erase it.
 */
static int get_saved_records(void)
{
        struct fru_rec *old, *new;
        u64 record_id;
        int ret, pos;
        ssize_t len;

        old = kmalloc(FMPM_MAX_REC_LEN, GFP_KERNEL);
        if (!old) {
                ret = -ENOMEM;
                goto out;
        }

        ret = erst_get_record_id_begin(&pos);
        if (ret < 0)
                goto out_end;

        while (!erst_get_record_id_next(&pos, &record_id)) {
                if (record_id == APEI_ERST_INVALID_RECORD_ID)
                        goto out_end;
                /*
                 * Make sure to clear temporary buffer between reads to avoid
                 * leftover data from records of various sizes.
                 */
                memset(old, 0, FMPM_MAX_REC_LEN);

                len = erst_read_record(record_id, &old->hdr, FMPM_MAX_REC_LEN,
                                       sizeof(struct fru_rec), &CPER_CREATOR_FMP);
                if (len < 0)
                        continue;

                new = get_valid_record(old);
                if (!new) {
                        erst_clear(record_id);
                        continue;
                }

                if (len > max_rec_len) {
                        unsigned int saved_nr_entries;

                        saved_nr_entries  = len - sizeof(struct fru_rec);
                        saved_nr_entries /= sizeof(struct cper_fru_poison_desc);

                        pr_warn("Saved record found with %u entries.\n", saved_nr_entries);
                        pr_warn("Please increase max_nr_entries to %u.\n", saved_nr_entries);

                        ret = -EINVAL;
                        goto out_end;
                }

                /* Restore the record */
                memcpy(new, old, len);
        }

out_end:
        erst_get_record_id_end();
        kfree(old);
out:
        return ret;
}

static void set_fmp_fields(struct fru_rec *rec, unsigned int cpu)
{
        struct cper_sec_fru_mem_poison *fmp = &rec->fmp;

        fmp->fru_arch_type    = FMP_ARCH_TYPE_X86_CPUID_1_EAX;
        fmp->validation_bits |= FMP_VALID_ARCH_TYPE;

        /* Assume all CPUs in the system have the same value for now. */
        fmp->fru_arch         = cpuid_eax(1);
        fmp->validation_bits |= FMP_VALID_ARCH;

        fmp->fru_id_type      = FMP_ID_TYPE_X86_PPIN;
        fmp->validation_bits |= FMP_VALID_ID_TYPE;

        fmp->fru_id           = topology_ppin(cpu);
        fmp->validation_bits |= FMP_VALID_ID;
}

static int init_fmps(void)
{
        struct fru_rec *rec;
        unsigned int i, cpu;
        int ret = 0;

        for_each_fru(i, rec) {
                unsigned int fru_cpu = INVALID_CPU;

                cpus_read_lock();
                for_each_online_cpu(cpu) {
                        if (topology_physical_package_id(cpu) == i) {
                                fru_cpu = cpu;
                                break;
                        }
                }
                cpus_read_unlock();

                if (fru_cpu == INVALID_CPU) {
                        pr_debug("Failed to find matching CPU for FRU #%u\n", i);
                        ret = -ENODEV;
                        break;
                }

                set_fmp_fields(rec, fru_cpu);
        }

        return ret;
}

static int get_system_info(void)
{
        /* Only load on MI300A systems for now. */
        if (!(boot_cpu_data.x86_model >= 0x90 &&
              boot_cpu_data.x86_model <= 0x9f))
                return -ENODEV;

        if (!cpu_feature_enabled(X86_FEATURE_AMD_PPIN)) {
                pr_debug("PPIN feature not available\n");
                return -ENODEV;
        }

        /* Use CPU socket as FRU for MI300 systems. */
        max_nr_fru = topology_max_packages();
        if (!max_nr_fru)
                return -ENODEV;

        if (max_nr_fru > FMPM_MAX_NR_FRU) {
                pr_warn("Too many FRUs to manage: found: %u, max: %u\n",
                        max_nr_fru, FMPM_MAX_NR_FRU);
                return -ENODEV;
        }

        if (!max_nr_entries)
                max_nr_entries = FMPM_DEFAULT_MAX_NR_ENTRIES;

        spa_nr_entries = max_nr_fru * max_nr_entries;

        max_rec_len  = sizeof(struct fru_rec);
        max_rec_len += sizeof(struct cper_fru_poison_desc) * max_nr_entries;

        pr_info("max FRUs: %u, max entries: %u, max record length: %lu\n",
                 max_nr_fru, max_nr_entries, max_rec_len);

        return 0;
}

static void free_records(void)
{
        struct fru_rec *rec;
        int i;

        for_each_fru(i, rec)
                kfree(rec);

        kfree(fru_records);
        kfree(spa_entries);
}

static int allocate_records(void)
{
        int i, ret = 0;

        fru_records = kzalloc_objs(struct fru_rec *, max_nr_fru);
        if (!fru_records) {
                ret = -ENOMEM;
                goto out;
        }

        for (i = 0; i < max_nr_fru; i++) {
                fru_records[i] = kzalloc(max_rec_len, GFP_KERNEL);
                if (!fru_records[i]) {
                        ret = -ENOMEM;
                        goto out_free;
                }
        }

        spa_entries = kcalloc(spa_nr_entries, sizeof(u64), GFP_KERNEL);
        if (!spa_entries) {
                ret = -ENOMEM;
                goto out_free;
        }

        for (i = 0; i < spa_nr_entries; i++)
                spa_entries[i] = INVALID_SPA;

        return ret;

out_free:
        while (--i >= 0)
                kfree(fru_records[i]);

        kfree(fru_records);
out:
        return ret;
}

static void *fmpm_start(struct seq_file *f, loff_t *pos)
{
        if (*pos >= (spa_nr_entries + 1))
                return NULL;
        return pos;
}

static void *fmpm_next(struct seq_file *f, void *data, loff_t *pos)
{
        if (++(*pos) >= (spa_nr_entries + 1))
                return NULL;
        return pos;
}

static void fmpm_stop(struct seq_file *f, void *data)
{
}

#define SHORT_WIDTH     8
#define U64_WIDTH       18
#define TIMESTAMP_WIDTH 19
#define LONG_WIDTH      24
#define U64_PAD         (LONG_WIDTH - U64_WIDTH)
#define TS_PAD          (LONG_WIDTH - TIMESTAMP_WIDTH)
static int fmpm_show(struct seq_file *f, void *data)
{
        unsigned int fru_idx, entry, spa_entry, line;
        struct cper_fru_poison_desc *fpd;
        struct fru_rec *rec;

        line = *(loff_t *)data;
        if (line == 0) {
                seq_printf(f, "%-*s", SHORT_WIDTH, "fru_idx");
                seq_printf(f, "%-*s", LONG_WIDTH,  "fru_id");
                seq_printf(f, "%-*s", SHORT_WIDTH, "entry");
                seq_printf(f, "%-*s", LONG_WIDTH,  "timestamp");
                seq_printf(f, "%-*s", LONG_WIDTH,  "hw_id");
                seq_printf(f, "%-*s", LONG_WIDTH,  "addr");
                seq_printf(f, "%-*s", LONG_WIDTH,  "spa");
                goto out_newline;
        }

        spa_entry = line - 1;
        fru_idx   = spa_entry / max_nr_entries;
        entry     = spa_entry % max_nr_entries;

        rec = fru_records[fru_idx];
        if (!rec)
                goto out;

        seq_printf(f, "%-*u",           SHORT_WIDTH, fru_idx);
        seq_printf(f, "0x%016llx%-*s",  rec->fmp.fru_id, U64_PAD, "");
        seq_printf(f, "%-*u",           SHORT_WIDTH, entry);

        mutex_lock(&fmpm_update_mutex);

        if (entry >= rec->fmp.nr_entries) {
                seq_printf(f, "%-*s", LONG_WIDTH, "*");
                seq_printf(f, "%-*s", LONG_WIDTH, "*");
                seq_printf(f, "%-*s", LONG_WIDTH, "*");
                seq_printf(f, "%-*s", LONG_WIDTH, "*");
                goto out_unlock;
        }

        fpd = &rec->entries[entry];

        seq_printf(f, "%ptT%-*s",       &fpd->timestamp, TS_PAD,  "");
        seq_printf(f, "0x%016llx%-*s",  fpd->hw_id,      U64_PAD, "");
        seq_printf(f, "0x%016llx%-*s",  fpd->addr,       U64_PAD, "");

        if (spa_entries[spa_entry] == INVALID_SPA)
                seq_printf(f, "%-*s", LONG_WIDTH, "*");
        else
                seq_printf(f, "0x%016llx%-*s", spa_entries[spa_entry], U64_PAD, "");

out_unlock:
        mutex_unlock(&fmpm_update_mutex);
out_newline:
        seq_putc(f, '\n');
out:
        return 0;
}

static const struct seq_operations fmpm_seq_ops = {
        .start  = fmpm_start,
        .next   = fmpm_next,
        .stop   = fmpm_stop,
        .show   = fmpm_show,
};

static int fmpm_open(struct inode *inode, struct file *file)
{
        return seq_open(file, &fmpm_seq_ops);
}

static const struct file_operations fmpm_fops = {
        .open           = fmpm_open,
        .release        = seq_release,
        .read           = seq_read,
        .llseek         = seq_lseek,
};

static void setup_debugfs(void)
{
        struct dentry *dfs = ras_get_debugfs_root();

        if (!dfs)
                return;

        fmpm_dfs_dir = debugfs_create_dir("fmpm", dfs);
        if (!fmpm_dfs_dir)
                return;

        fmpm_dfs_entries = debugfs_create_file("entries", 0400, fmpm_dfs_dir, NULL, &fmpm_fops);
        if (!fmpm_dfs_entries)
                debugfs_remove(fmpm_dfs_dir);
}

static const struct x86_cpu_id fmpm_cpuids[] = {
        X86_MATCH_VENDOR_FAM(AMD, 0x19, NULL),
        { }
};
MODULE_DEVICE_TABLE(x86cpu, fmpm_cpuids);

static int __init fru_mem_poison_init(void)
{
        int ret;

        if (!x86_match_cpu(fmpm_cpuids)) {
                ret = -ENODEV;
                goto out;
        }

        if (erst_disable) {
                pr_debug("ERST not available\n");
                ret = -ENODEV;
                goto out;
        }

        ret = get_system_info();
        if (ret)
                goto out;

        ret = allocate_records();
        if (ret)
                goto out;

        ret = init_fmps();
        if (ret)
                goto out_free;

        ret = get_saved_records();
        if (ret)
                goto out_free;

        ret = save_new_records();
        if (ret)
                goto out_free;

        setup_debugfs();

        retire_mem_records();

        mce_register_decode_chain(&fru_mem_poison_nb);

        pr_info("FRU Memory Poison Manager initialized\n");
        return 0;

out_free:
        free_records();
out:
        return ret;
}

static void __exit fru_mem_poison_exit(void)
{
        mce_unregister_decode_chain(&fru_mem_poison_nb);
        debugfs_remove(fmpm_dfs_dir);
        free_records();
}

module_init(fru_mem_poison_init);
module_exit(fru_mem_poison_exit);

MODULE_LICENSE("GPL");
MODULE_DESCRIPTION("FRU Memory Poison Manager");