nvram.c

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/*
 *  c 2001 PPC 64 Team, IBM Corp
 *
 *      This program is free software; you can redistribute it and/or
 *      modify it under the terms of the GNU General Public License
 *      as published by the Free Software Foundation; either version
 *      2 of the License, or (at your option) any later version.
 *
 * /dev/nvram driver for PPC64
 *
 * This perhaps should live in drivers/char
 */


#include <linux/types.h>
#include <linux/errno.h>
#include <linux/init.h>
#include <linux/spinlock.h>
#include <linux/slab.h>
#include <linux/kmsg_dump.h>
#include <linux/ctype.h>
#include <linux/zlib.h>
#include <asm/uaccess.h>
#include <asm/nvram.h>
#include <asm/rtas.h>
#include <asm/prom.h>
#include <asm/machdep.h>

/* Max bytes to read/write in one go */
#define NVRW_CNT 0x20

static unsigned int nvram_size;
static int nvram_fetch, nvram_store;
static char nvram_buf[NVRW_CNT];    /* assume this is in the first 4GB */
static DEFINE_SPINLOCK(nvram_lock);

struct err_log_info {
    int error_type;
    unsigned int seq_num;
};

struct nvram_os_partition {
    const char *name;
    int req_size;   /* desired size, in bytes */
    int min_size;   /* minimum acceptable size (0 means req_size) */
    long size;  /* size of data portion (excluding err_log_info) */
    long index; /* offset of data portion of partition */
};

static struct nvram_os_partition rtas_log_partition = {
    .name = "ibm,rtas-log",
    .req_size = 2079,
    .min_size = 1055,
    .index = -1
};

static struct nvram_os_partition oops_log_partition = {
    .name = "lnx,oops-log",
    .req_size = 4000,
    .min_size = 2000,
    .index = -1
};

static const char *pseries_nvram_os_partitions[] = {
    "ibm,rtas-log",
    "lnx,oops-log",
    NULL
};

static void oops_to_nvram(struct kmsg_dumper *dumper,
              enum kmsg_dump_reason reason);

static struct kmsg_dumper nvram_kmsg_dumper = {
    .dump = oops_to_nvram
};

/* See clobbering_unread_rtas_event() */
#define NVRAM_RTAS_READ_TIMEOUT 5       /* seconds */
static unsigned long last_unread_rtas_event;    /* timestamp */

/*
 * For capturing and compressing an oops or panic report...

 * big_oops_buf[] holds the uncompressed text we're capturing.
 *
 * oops_buf[] holds the compressed text, preceded by a prefix.
 * The prefix is just a u16 holding the length of the compressed* text.
 * (*Or uncompressed, if compression fails.)  oops_buf[] gets written
 * to NVRAM.
 *
 * oops_len points to the prefix.  oops_data points to the compressed text.
 *
 * +- oops_buf
 * |        +- oops_data
 * v        v
 * +------------+-----------------------------------------------+
 * | length | text                                          |
 * | (2 bytes)  | (oops_data_sz bytes)                          |
 * +------------+-----------------------------------------------+
 * ^
 * +- oops_len
 *
 * We preallocate these buffers during init to avoid kmalloc during oops/panic.
 */
static size_t big_oops_buf_sz;
static char *big_oops_buf, *oops_buf;
static u16 *oops_len;
static char *oops_data;
static size_t oops_data_sz;

/* Compression parameters */
#define COMPR_LEVEL 6
#define WINDOW_BITS 12
#define MEM_LEVEL 4
static struct z_stream_s stream;

static ssize_t pSeries_nvram_read(char *buf, size_t count, loff_t *index)
{
    unsigned int i;
    unsigned long len;
    int done;
    unsigned long flags;
    char *p = buf;


    if (nvram_size == 0 || nvram_fetch == RTAS_UNKNOWN_SERVICE)
        return -ENODEV;

    if (*index >= nvram_size)
        return 0;

    i = *index;
    if (i + count > nvram_size)
        count = nvram_size - i;

    spin_lock_irqsave(&nvram_lock, flags);

    for (; count != 0; count -= len) {
        len = count;
        if (len > NVRW_CNT)
            len = NVRW_CNT;
        
        if ((rtas_call(nvram_fetch, 3, 2, &done, i, __pa(nvram_buf),
                   len) != 0) || len != done) {
            spin_unlock_irqrestore(&nvram_lock, flags);
            return -EIO;
        }
        
        memcpy(p, nvram_buf, len);

        p += len;
        i += len;
    }

    spin_unlock_irqrestore(&nvram_lock, flags);
    
    *index = i;
    return p - buf;
}

static ssize_t pSeries_nvram_write(char *buf, size_t count, loff_t *index)
{
    unsigned int i;
    unsigned long len;
    int done;
    unsigned long flags;
    const char *p = buf;

    if (nvram_size == 0 || nvram_store == RTAS_UNKNOWN_SERVICE)
        return -ENODEV;

    if (*index >= nvram_size)
        return 0;

    i = *index;
    if (i + count > nvram_size)
        count = nvram_size - i;

    spin_lock_irqsave(&nvram_lock, flags);

    for (; count != 0; count -= len) {
        len = count;
        if (len > NVRW_CNT)
            len = NVRW_CNT;

        memcpy(nvram_buf, p, len);

        if ((rtas_call(nvram_store, 3, 2, &done, i, __pa(nvram_buf),
                   len) != 0) || len != done) {
            spin_unlock_irqrestore(&nvram_lock, flags);
            return -EIO;
        }
        
        p += len;
        i += len;
    }
    spin_unlock_irqrestore(&nvram_lock, flags);
    
    *index = i;
    return p - buf;
}

static ssize_t pSeries_nvram_get_size(void)
{
    return nvram_size ? nvram_size : -ENODEV;
}


/* nvram_write_os_partition, nvram_write_error_log
 *
 * We need to buffer the error logs into nvram to ensure that we have
 * the failure information to decode.  If we have a severe error there
 * is no way to guarantee that the OS or the machine is in a state to
 * get back to user land and write the error to disk.  For example if
 * the SCSI device driver causes a Machine Check by writing to a bad
 * IO address, there is no way of guaranteeing that the device driver
 * is in any state that is would also be able to write the error data
 * captured to disk, thus we buffer it in NVRAM for analysis on the
 * next boot.
 *
 * In NVRAM the partition containing the error log buffer will looks like:
 * Header (in bytes):
 * +-----------+----------+--------+------------+------------------+
 * | signature | checksum | length | name       | data             |
 * |0          |1         |2      3|4         15|16        length-1|
 * +-----------+----------+--------+------------+------------------+
 *
 * The 'data' section would look like (in bytes):
 * +--------------+------------+-----------------------------------+
 * | event_logged | sequence # | error log                         |
 * |0            3|4          7|8                  error_log_size-1|
 * +--------------+------------+-----------------------------------+
 *
 * event_logged: 0 if event has not been logged to syslog, 1 if it has
 * sequence #: The unique sequence # for each event. (until it wraps)
 * error log: The error log from event_scan
 */
int nvram_write_os_partition(struct nvram_os_partition *part, char * buff,
        int length, unsigned int err_type, unsigned int error_log_cnt)
{
    int rc;
    loff_t tmp_index;
    struct err_log_info info;
    
    if (part->index == -1) {
        return -ESPIPE;
    }

    if (length > part->size) {
        length = part->size;
    }

    info.error_type = err_type;
    info.seq_num = error_log_cnt;

    tmp_index = part->index;

    rc = ppc_md.nvram_write((char *)&info, sizeof(struct err_log_info), &tmp_index);
    if (rc <= 0) {
        pr_err("%s: Failed nvram_write (%d)\n", __FUNCTION__, rc);
        return rc;
    }

    rc = ppc_md.nvram_write(buff, length, &tmp_index);
    if (rc <= 0) {
        pr_err("%s: Failed nvram_write (%d)\n", __FUNCTION__, rc);
        return rc;
    }
    
    return 0;
}

int nvram_write_error_log(char * buff, int length,
                          unsigned int err_type, unsigned int error_log_cnt)
{
    int rc = nvram_write_os_partition(&rtas_log_partition, buff, length,
                        err_type, error_log_cnt);
    if (!rc)
        last_unread_rtas_event = get_seconds();
    return rc;
}

/* nvram_read_error_log
 *
 * Reads nvram for error log for at most 'length'
 */
int nvram_read_error_log(char * buff, int length,
                         unsigned int * err_type, unsigned int * error_log_cnt)
{
    int rc;
    loff_t tmp_index;
    struct err_log_info info;
    
    if (rtas_log_partition.index == -1)
        return -1;

    if (length > rtas_log_partition.size)
        length = rtas_log_partition.size;

    tmp_index = rtas_log_partition.index;

    rc = ppc_md.nvram_read((char *)&info, sizeof(struct err_log_info), &tmp_index);
    if (rc <= 0) {
        printk(KERN_ERR "nvram_read_error_log: Failed nvram_read (%d)\n", rc);
        return rc;
    }

    rc = ppc_md.nvram_read(buff, length, &tmp_index);
    if (rc <= 0) {
        printk(KERN_ERR "nvram_read_error_log: Failed nvram_read (%d)\n", rc);
        return rc;
    }

    *error_log_cnt = info.seq_num;
    *err_type = info.error_type;

    return 0;
}

/* This doesn't actually zero anything, but it sets the event_logged
 * word to tell that this event is safely in syslog.
 */
int nvram_clear_error_log(void)
{
    loff_t tmp_index;
    int clear_word = ERR_FLAG_ALREADY_LOGGED;
    int rc;

    if (rtas_log_partition.index == -1)
        return -1;

    tmp_index = rtas_log_partition.index;
    
    rc = ppc_md.nvram_write((char *)&clear_word, sizeof(int), &tmp_index);
    if (rc <= 0) {
        printk(KERN_ERR "nvram_clear_error_log: Failed nvram_write (%d)\n", rc);
        return rc;
    }
    last_unread_rtas_event = 0;

    return 0;
}

/* pseries_nvram_init_os_partition
 *
 * This sets up a partition with an "OS" signature.
 *
 * The general strategy is the following:
 * 1.) If a partition with the indicated name already exists...
 *  - If it's large enough, use it.
 *  - Otherwise, recycle it and keep going.
 * 2.) Search for a free partition that is large enough.
 * 3.) If there's not a free partition large enough, recycle any obsolete
 * OS partitions and try again.
 * 4.) Will first try getting a chunk that will satisfy the requested size.
 * 5.) If a chunk of the requested size cannot be allocated, then try finding
 * a chunk that will satisfy the minum needed.
 *
 * Returns 0 on success, else -1.
 */
static int __init pseries_nvram_init_os_partition(struct nvram_os_partition
                                    *part)
{
    loff_t p;
    int size;

    /* Scan nvram for partitions */
    nvram_scan_partitions();

    /* Look for ours */
    p = nvram_find_partition(part->name, NVRAM_SIG_OS, &size);

    /* Found one but too small, remove it */
    if (p && size < part->min_size) {
        pr_info("nvram: Found too small %s partition,"
                    " removing it...\n", part->name);
        nvram_remove_partition(part->name, NVRAM_SIG_OS, NULL);
        p = 0;
    }

    /* Create one if we didn't find */
    if (!p) {
        p = nvram_create_partition(part->name, NVRAM_SIG_OS,
                    part->req_size, part->min_size);
        if (p == -ENOSPC) {
            pr_info("nvram: No room to create %s partition, "
                "deleting any obsolete OS partitions...\n",
                part->name);
            nvram_remove_partition(NULL, NVRAM_SIG_OS,
                        pseries_nvram_os_partitions);
            p = nvram_create_partition(part->name, NVRAM_SIG_OS,
                    part->req_size, part->min_size);
        }
    }

    if (p <= 0) {
        pr_err("nvram: Failed to find or create %s"
               " partition, err %d\n", part->name, (int)p);
        return -1;
    }

    part->index = p;
    part->size = nvram_get_partition_size(p) - sizeof(struct err_log_info);
    
    return 0;
}

static void __init nvram_init_oops_partition(int rtas_partition_exists)
{
    int rc;

    rc = pseries_nvram_init_os_partition(&oops_log_partition);
    if (rc != 0) {
        if (!rtas_partition_exists)
            return;
        pr_notice("nvram: Using %s partition to log both"
            " RTAS errors and oops/panic reports\n",
            rtas_log_partition.name);
        memcpy(&oops_log_partition, &rtas_log_partition,
                        sizeof(rtas_log_partition));
    }
    oops_buf = kmalloc(oops_log_partition.size, GFP_KERNEL);
    if (!oops_buf) {
        pr_err("nvram: No memory for %s partition\n",
                        oops_log_partition.name);
        return;
    }
    oops_len = (u16*) oops_buf;
    oops_data = oops_buf + sizeof(u16);
    oops_data_sz = oops_log_partition.size - sizeof(u16);

    /*
     * Figure compression (preceded by elimination of each line's <n>
     * severity prefix) will reduce the oops/panic report to at most
     * 45% of its original size.
     */
    big_oops_buf_sz = (oops_data_sz * 100) / 45;
    big_oops_buf = kmalloc(big_oops_buf_sz, GFP_KERNEL);
    if (big_oops_buf) {
        stream.workspace = kmalloc(zlib_deflate_workspacesize(
                WINDOW_BITS, MEM_LEVEL), GFP_KERNEL);
        if (!stream.workspace) {
            pr_err("nvram: No memory for compression workspace; "
                "skipping compression of %s partition data\n",
                oops_log_partition.name);
            kfree(big_oops_buf);
            big_oops_buf = NULL;
        }
    } else {
        pr_err("No memory for uncompressed %s data; "
            "skipping compression\n", oops_log_partition.name);
        stream.workspace = NULL;
    }

    rc = kmsg_dump_register(&nvram_kmsg_dumper);
    if (rc != 0) {
        pr_err("nvram: kmsg_dump_register() failed; returned %d\n", rc);
        kfree(oops_buf);
        kfree(big_oops_buf);
        kfree(stream.workspace);
    }
}

static int __init pseries_nvram_init_log_partitions(void)
{
    int rc;

    rc = pseries_nvram_init_os_partition(&rtas_log_partition);
    nvram_init_oops_partition(rc == 0);
    return 0;
}
machine_arch_initcall(pseries, pseries_nvram_init_log_partitions);

int __init pSeries_nvram_init(void)
{
    struct device_node *nvram;
    const unsigned int *nbytes_p;
    unsigned int proplen;

    nvram = of_find_node_by_type(NULL, "nvram");
    if (nvram == NULL)
        return -ENODEV;

    nbytes_p = of_get_property(nvram, "#bytes", &proplen);
    if (nbytes_p == NULL || proplen != sizeof(unsigned int)) {
        of_node_put(nvram);
        return -EIO;
    }

    nvram_size = *nbytes_p;

    nvram_fetch = rtas_token("nvram-fetch");
    nvram_store = rtas_token("nvram-store");
    printk(KERN_INFO "PPC64 nvram contains %d bytes\n", nvram_size);
    of_node_put(nvram);

    ppc_md.nvram_read   = pSeries_nvram_read;
    ppc_md.nvram_write  = pSeries_nvram_write;
    ppc_md.nvram_size   = pSeries_nvram_get_size;

    return 0;
}

/*
 * Are we using the ibm,rtas-log for oops/panic reports?  And if so,
 * would logging this oops/panic overwrite an RTAS event that rtas_errd
 * hasn't had a chance to read and process?  Return 1 if so, else 0.
 *
 * We assume that if rtas_errd hasn't read the RTAS event in
 * NVRAM_RTAS_READ_TIMEOUT seconds, it's probably not going to.
 */
static int clobbering_unread_rtas_event(void)
{
    return (oops_log_partition.index == rtas_log_partition.index
        && last_unread_rtas_event
        && get_seconds() - last_unread_rtas_event <=
                        NVRAM_RTAS_READ_TIMEOUT);
}

/* Derived from logfs_compress() */
static int nvram_compress(const void *in, void *out, size_t inlen,
                            size_t outlen)
{
    int err, ret;

    ret = -EIO;
    err = zlib_deflateInit2(&stream, COMPR_LEVEL, Z_DEFLATED, WINDOW_BITS,
                        MEM_LEVEL, Z_DEFAULT_STRATEGY);
    if (err != Z_OK)
        goto error;

    stream.next_in = in;
    stream.avail_in = inlen;
    stream.total_in = 0;
    stream.next_out = out;
    stream.avail_out = outlen;
    stream.total_out = 0;

    err = zlib_deflate(&stream, Z_FINISH);
    if (err != Z_STREAM_END)
        goto error;

    err = zlib_deflateEnd(&stream);
    if (err != Z_OK)
        goto error;

    if (stream.total_out >= stream.total_in)
        goto error;

    ret = stream.total_out;
error:
    return ret;
}

/* Compress the text from big_oops_buf into oops_buf. */
static int zip_oops(size_t text_len)
{
    int zipped_len = nvram_compress(big_oops_buf, oops_data, text_len,
                                oops_data_sz);
    if (zipped_len < 0) {
        pr_err("nvram: compression failed; returned %d\n", zipped_len);
        pr_err("nvram: logging uncompressed oops/panic report\n");
        return -1;
    }
    *oops_len = (u16) zipped_len;
    return 0;
}

/*
 * This is our kmsg_dump callback, called after an oops or panic report
 * has been written to the printk buffer.  We want to capture as much
 * of the printk buffer as possible.  First, capture as much as we can
 * that we think will compress sufficiently to fit in the lnx,oops-log
 * partition.  If that's too much, go back and capture uncompressed text.
 */
static void oops_to_nvram(struct kmsg_dumper *dumper,
              enum kmsg_dump_reason reason)
{
    static unsigned int oops_count = 0;
    static bool panicking = false;
    static DEFINE_SPINLOCK(lock);
    unsigned long flags;
    size_t text_len;
    unsigned int err_type = ERR_TYPE_KERNEL_PANIC_GZ;
    int rc = -1;

    switch (reason) {
    case KMSG_DUMP_RESTART:
    case KMSG_DUMP_HALT:
    case KMSG_DUMP_POWEROFF:
        /* These are almost always orderly shutdowns. */
        return;
    case KMSG_DUMP_OOPS:
        break;
    case KMSG_DUMP_PANIC:
        panicking = true;
        break;
    case KMSG_DUMP_EMERG:
        if (panicking)
            /* Panic report already captured. */
            return;
        break;
    default:
        pr_err("%s: ignoring unrecognized KMSG_DUMP_* reason %d\n",
                        __FUNCTION__, (int) reason);
        return;
    }

    if (clobbering_unread_rtas_event())
        return;

    if (!spin_trylock_irqsave(&lock, flags))
        return;

    if (big_oops_buf) {
        kmsg_dump_get_buffer(dumper, false,
                     big_oops_buf, big_oops_buf_sz, &text_len);
        rc = zip_oops(text_len);
    }
    if (rc != 0) {
        kmsg_dump_rewind(dumper);
        kmsg_dump_get_buffer(dumper, true,
                     oops_data, oops_data_sz, &text_len);
        err_type = ERR_TYPE_KERNEL_PANIC;
        *oops_len = (u16) text_len;
    }

    (void) nvram_write_os_partition(&oops_log_partition, oops_buf,
        (int) (sizeof(*oops_len) + *oops_len), err_type, ++oops_count);

    spin_unlock_irqrestore(&lock, flags);
}