salinfo.c

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/*
 * salinfo.c
 *
 * Creates entries in /proc/sal for various system features.
 *
 * Copyright (c) 2003, 2006 Silicon Graphics, Inc.  All rights reserved.
 * Copyright (c) 2003 Hewlett-Packard Co
 *  Bjorn Helgaas <[email protected]>
 *
 * 10/30/2001   [email protected]     copied much of Stephane's palinfo
 *                  code to create this file
 * Oct 23 2003  [email protected]
 *   Replace IPI with set_cpus_allowed() to read a record from the required cpu.
 *   Redesign salinfo log processing to separate interrupt and user space
 *   contexts.
 *   Cache the record across multi-block reads from user space.
 *   Support > 64 cpus.
 *   Delete module_exit and MOD_INC/DEC_COUNT, salinfo cannot be a module.
 *
 * Jan 28 2004  [email protected]
 *   Periodically check for outstanding MCA or INIT records.
 *
 * Dec  5 2004  [email protected]
 *   Standardize which records are cleared automatically.
 *
 * Aug 18 2005  [email protected]
 *   mca.c may not pass a buffer, a NULL buffer just indicates that a new
 *   record is available in SAL.
 *   Replace some NR_CPUS by cpus_online, for hotplug cpu.
 *
 * Jan  5 2006        [email protected]
 *   Handle hotplug cpus coming online.
 *   Handle hotplug cpus going offline while they still have outstanding records.
 *   Use the cpu_* macros consistently.
 *   Replace the counting semaphore with a mutex and a test if the cpumask is non-empty.
 *   Modify the locking to make the test for "work to do" an atomic operation.
 */

#include <linux/capability.h>
#include <linux/cpu.h>
#include <linux/types.h>
#include <linux/proc_fs.h>
#include <linux/module.h>
#include <linux/smp.h>
#include <linux/timer.h>
#include <linux/vmalloc.h>
#include <linux/semaphore.h>

#include <asm/sal.h>
#include <asm/uaccess.h>

MODULE_AUTHOR("Jesse Barnes <[email protected]>");
MODULE_DESCRIPTION("/proc interface to IA-64 SAL features");
MODULE_LICENSE("GPL");

static int salinfo_read(char *page, char **start, off_t off, int count, int *eof, void *data);

typedef struct {
    const char      *name;      /* name of the proc entry */
    unsigned long           feature;        /* feature bit */
    struct proc_dir_entry   *entry;     /* registered entry (removal) */
} salinfo_entry_t;

/*
 * List {name,feature} pairs for every entry in /proc/sal/<feature>
 * that this module exports
 */
static salinfo_entry_t salinfo_entries[]={
    { "bus_lock",           IA64_SAL_PLATFORM_FEATURE_BUS_LOCK, },
    { "irq_redirection",    IA64_SAL_PLATFORM_FEATURE_IRQ_REDIR_HINT, },
    { "ipi_redirection",    IA64_SAL_PLATFORM_FEATURE_IPI_REDIR_HINT, },
    { "itc_drift",      IA64_SAL_PLATFORM_FEATURE_ITC_DRIFT, },
};

#define NR_SALINFO_ENTRIES ARRAY_SIZE(salinfo_entries)

static char *salinfo_log_name[] = {
    "mca",
    "init",
    "cmc",
    "cpe",
};

static struct proc_dir_entry *salinfo_proc_entries[
    ARRAY_SIZE(salinfo_entries) +           /* /proc/sal/bus_lock */
    ARRAY_SIZE(salinfo_log_name) +          /* /proc/sal/{mca,...} */
    (2 * ARRAY_SIZE(salinfo_log_name)) +        /* /proc/sal/mca/{event,data} */
    1];                     /* /proc/sal */

/* Some records we get ourselves, some are accessed as saved data in buffers
 * that are owned by mca.c.
 */
struct salinfo_data_saved {
    u8*         buffer;
    u64         size;
    u64         id;
    int         cpu;
};

/* State transitions.  Actions are :-
 *   Write "read <cpunum>" to the data file.
 *   Write "clear <cpunum>" to the data file.
 *   Write "oemdata <cpunum> <offset> to the data file.
 *   Read from the data file.
 *   Close the data file.
 *
 * Start state is NO_DATA.
 *
 * NO_DATA
 *    write "read <cpunum>" -> NO_DATA or LOG_RECORD.
 *    write "clear <cpunum>" -> NO_DATA or LOG_RECORD.
 *    write "oemdata <cpunum> <offset> -> return -EINVAL.
 *    read data -> return EOF.
 *    close -> unchanged.  Free record areas.
 *
 * LOG_RECORD
 *    write "read <cpunum>" -> NO_DATA or LOG_RECORD.
 *    write "clear <cpunum>" -> NO_DATA or LOG_RECORD.
 *    write "oemdata <cpunum> <offset> -> format the oem data, goto OEMDATA.
 *    read data -> return the INIT/MCA/CMC/CPE record.
 *    close -> unchanged.  Keep record areas.
 *
 * OEMDATA
 *    write "read <cpunum>" -> NO_DATA or LOG_RECORD.
 *    write "clear <cpunum>" -> NO_DATA or LOG_RECORD.
 *    write "oemdata <cpunum> <offset> -> format the oem data, goto OEMDATA.
 *    read data -> return the formatted oemdata.
 *    close -> unchanged.  Keep record areas.
 *
 * Closing the data file does not change the state.  This allows shell scripts
 * to manipulate salinfo data, each shell redirection opens the file, does one
 * action then closes it again.  The record areas are only freed at close when
 * the state is NO_DATA.
 */
enum salinfo_state {
    STATE_NO_DATA,
    STATE_LOG_RECORD,
    STATE_OEMDATA,
};

struct salinfo_data {
    cpumask_t       cpu_event;  /* which cpus have outstanding events */
    struct semaphore    mutex;
    u8          *log_buffer;
    u64         log_size;
    u8          *oemdata;   /* decoded oem data */
    u64         oemdata_size;
    int         open;       /* single-open to prevent races */
    u8          type;
    u8          saved_num;  /* using a saved record? */
    enum salinfo_state  state :8;   /* processing state */
    u8          padding;
    int         cpu_check;  /* next CPU to check */
    struct salinfo_data_saved data_saved[5];/* save last 5 records from mca.c, must be < 255 */
};

static struct salinfo_data salinfo_data[ARRAY_SIZE(salinfo_log_name)];

static DEFINE_SPINLOCK(data_lock);
static DEFINE_SPINLOCK(data_saved_lock);

int (*salinfo_platform_oemdata)(const u8 *sect_header, u8 **oemdata, u64 *oemdata_size);

struct salinfo_platform_oemdata_parms {
    const u8 *efi_guid;
    u8 **oemdata;
    u64 *oemdata_size;
    int ret;
};

/* Kick the mutex that tells user space that there is work to do.  Instead of
 * trying to track the state of the mutex across multiple cpus, in user
 * context, interrupt context, non-maskable interrupt context and hotplug cpu,
 * it is far easier just to grab the mutex if it is free then release it.
 *
 * This routine must be called with data_saved_lock held, to make the down/up
 * operation atomic.
 */
static void
salinfo_work_to_do(struct salinfo_data *data)
{
    (void)(down_trylock(&data->mutex) ?: 0);
    up(&data->mutex);
}

static void
salinfo_platform_oemdata_cpu(void *context)
{
    struct salinfo_platform_oemdata_parms *parms = context;
    parms->ret = salinfo_platform_oemdata(parms->efi_guid, parms->oemdata, parms->oemdata_size);
}

static void
shift1_data_saved (struct salinfo_data *data, int shift)
{
    memcpy(data->data_saved+shift, data->data_saved+shift+1,
           (ARRAY_SIZE(data->data_saved) - (shift+1)) * sizeof(data->data_saved[0]));
    memset(data->data_saved + ARRAY_SIZE(data->data_saved) - 1, 0,
           sizeof(data->data_saved[0]));
}

/* This routine is invoked in interrupt context.  Note: mca.c enables
 * interrupts before calling this code for CMC/CPE.  MCA and INIT events are
 * not irq safe, do not call any routines that use spinlocks, they may deadlock.
 * MCA and INIT records are recorded, a timer event will look for any
 * outstanding events and wake up the user space code.
 *
 * The buffer passed from mca.c points to the output from ia64_log_get. This is
 * a persistent buffer but its contents can change between the interrupt and
 * when user space processes the record.  Save the record id to identify
 * changes.  If the buffer is NULL then just update the bitmap.
 */
void
salinfo_log_wakeup(int type, u8 *buffer, u64 size, int irqsafe)
{
    struct salinfo_data *data = salinfo_data + type;
    struct salinfo_data_saved *data_saved;
    unsigned long flags = 0;
    int i;
    int saved_size = ARRAY_SIZE(data->data_saved);

    BUG_ON(type >= ARRAY_SIZE(salinfo_log_name));

    if (irqsafe)
        spin_lock_irqsave(&data_saved_lock, flags);
    if (buffer) {
        for (i = 0, data_saved = data->data_saved; i < saved_size; ++i, ++data_saved) {
            if (!data_saved->buffer)
                break;
        }
        if (i == saved_size) {
            if (!data->saved_num) {
                shift1_data_saved(data, 0);
                data_saved = data->data_saved + saved_size - 1;
            } else
                data_saved = NULL;
        }
        if (data_saved) {
            data_saved->cpu = smp_processor_id();
            data_saved->id = ((sal_log_record_header_t *)buffer)->id;
            data_saved->size = size;
            data_saved->buffer = buffer;
        }
    }
    cpu_set(smp_processor_id(), data->cpu_event);
    if (irqsafe) {
        salinfo_work_to_do(data);
        spin_unlock_irqrestore(&data_saved_lock, flags);
    }
}

/* Check for outstanding MCA/INIT records every minute (arbitrary) */
#define SALINFO_TIMER_DELAY (60*HZ)
static struct timer_list salinfo_timer;
extern void ia64_mlogbuf_dump(void);

static void
salinfo_timeout_check(struct salinfo_data *data)
{
    unsigned long flags;
    if (!data->open)
        return;
    if (!cpus_empty(data->cpu_event)) {
        spin_lock_irqsave(&data_saved_lock, flags);
        salinfo_work_to_do(data);
        spin_unlock_irqrestore(&data_saved_lock, flags);
    }
}

static void
salinfo_timeout (unsigned long arg)
{
    ia64_mlogbuf_dump();
    salinfo_timeout_check(salinfo_data + SAL_INFO_TYPE_MCA);
    salinfo_timeout_check(salinfo_data + SAL_INFO_TYPE_INIT);
    salinfo_timer.expires = jiffies + SALINFO_TIMER_DELAY;
    add_timer(&salinfo_timer);
}

static int
salinfo_event_open(struct inode *inode, struct file *file)
{
    if (!capable(CAP_SYS_ADMIN))
        return -EPERM;
    return 0;
}

static ssize_t
salinfo_event_read(struct file *file, char __user *buffer, size_t count, loff_t *ppos)
{
    struct inode *inode = file->f_path.dentry->d_inode;
    struct proc_dir_entry *entry = PDE(inode);
    struct salinfo_data *data = entry->data;
    char cmd[32];
    size_t size;
    int i, n, cpu = -1;

retry:
    if (cpus_empty(data->cpu_event) && down_trylock(&data->mutex)) {
        if (file->f_flags & O_NONBLOCK)
            return -EAGAIN;
        if (down_interruptible(&data->mutex))
            return -EINTR;
    }

    n = data->cpu_check;
    for (i = 0; i < nr_cpu_ids; i++) {
        if (cpu_isset(n, data->cpu_event)) {
            if (!cpu_online(n)) {
                cpu_clear(n, data->cpu_event);
                continue;
            }
            cpu = n;
            break;
        }
        if (++n == nr_cpu_ids)
            n = 0;
    }

    if (cpu == -1)
        goto retry;

    ia64_mlogbuf_dump();

    /* for next read, start checking at next CPU */
    data->cpu_check = cpu;
    if (++data->cpu_check == nr_cpu_ids)
        data->cpu_check = 0;

    snprintf(cmd, sizeof(cmd), "read %d\n", cpu);

    size = strlen(cmd);
    if (size > count)
        size = count;
    if (copy_to_user(buffer, cmd, size))
        return -EFAULT;

    return size;
}

static const struct file_operations salinfo_event_fops = {
    .open  = salinfo_event_open,
    .read  = salinfo_event_read,
    .llseek = noop_llseek,
};

static int
salinfo_log_open(struct inode *inode, struct file *file)
{
    struct proc_dir_entry *entry = PDE(inode);
    struct salinfo_data *data = entry->data;

    if (!capable(CAP_SYS_ADMIN))
        return -EPERM;

    spin_lock(&data_lock);
    if (data->open) {
        spin_unlock(&data_lock);
        return -EBUSY;
    }
    data->open = 1;
    spin_unlock(&data_lock);

    if (data->state == STATE_NO_DATA &&
        !(data->log_buffer = vmalloc(ia64_sal_get_state_info_size(data->type)))) {
        data->open = 0;
        return -ENOMEM;
    }

    return 0;
}

static int
salinfo_log_release(struct inode *inode, struct file *file)
{
    struct proc_dir_entry *entry = PDE(inode);
    struct salinfo_data *data = entry->data;

    if (data->state == STATE_NO_DATA) {
        vfree(data->log_buffer);
        vfree(data->oemdata);
        data->log_buffer = NULL;
        data->oemdata = NULL;
    }
    spin_lock(&data_lock);
    data->open = 0;
    spin_unlock(&data_lock);
    return 0;
}

static void
call_on_cpu(int cpu, void (*fn)(void *), void *arg)
{
    cpumask_t save_cpus_allowed = current->cpus_allowed;
    set_cpus_allowed_ptr(current, cpumask_of(cpu));
    (*fn)(arg);
    set_cpus_allowed_ptr(current, &save_cpus_allowed);
}

static void
salinfo_log_read_cpu(void *context)
{
    struct salinfo_data *data = context;
    sal_log_record_header_t *rh;
    data->log_size = ia64_sal_get_state_info(data->type, (u64 *) data->log_buffer);
    rh = (sal_log_record_header_t *)(data->log_buffer);
    /* Clear corrected errors as they are read from SAL */
    if (rh->severity == sal_log_severity_corrected)
        ia64_sal_clear_state_info(data->type);
}

static void
salinfo_log_new_read(int cpu, struct salinfo_data *data)
{
    struct salinfo_data_saved *data_saved;
    unsigned long flags;
    int i;
    int saved_size = ARRAY_SIZE(data->data_saved);

    data->saved_num = 0;
    spin_lock_irqsave(&data_saved_lock, flags);
retry:
    for (i = 0, data_saved = data->data_saved; i < saved_size; ++i, ++data_saved) {
        if (data_saved->buffer && data_saved->cpu == cpu) {
            sal_log_record_header_t *rh = (sal_log_record_header_t *)(data_saved->buffer);
            data->log_size = data_saved->size;
            memcpy(data->log_buffer, rh, data->log_size);
            barrier();  /* id check must not be moved */
            if (rh->id == data_saved->id) {
                data->saved_num = i+1;
                break;
            }
            /* saved record changed by mca.c since interrupt, discard it */
            shift1_data_saved(data, i);
            goto retry;
        }
    }
    spin_unlock_irqrestore(&data_saved_lock, flags);

    if (!data->saved_num)
        call_on_cpu(cpu, salinfo_log_read_cpu, data);
    if (!data->log_size) {
        data->state = STATE_NO_DATA;
        cpu_clear(cpu, data->cpu_event);
    } else {
        data->state = STATE_LOG_RECORD;
    }
}

static ssize_t
salinfo_log_read(struct file *file, char __user *buffer, size_t count, loff_t *ppos)
{
    struct inode *inode = file->f_path.dentry->d_inode;
    struct proc_dir_entry *entry = PDE(inode);
    struct salinfo_data *data = entry->data;
    u8 *buf;
    u64 bufsize;

    if (data->state == STATE_LOG_RECORD) {
        buf = data->log_buffer;
        bufsize = data->log_size;
    } else if (data->state == STATE_OEMDATA) {
        buf = data->oemdata;
        bufsize = data->oemdata_size;
    } else {
        buf = NULL;
        bufsize = 0;
    }
    return simple_read_from_buffer(buffer, count, ppos, buf, bufsize);
}

static void
salinfo_log_clear_cpu(void *context)
{
    struct salinfo_data *data = context;
    ia64_sal_clear_state_info(data->type);
}

static int
salinfo_log_clear(struct salinfo_data *data, int cpu)
{
    sal_log_record_header_t *rh;
    unsigned long flags;
    spin_lock_irqsave(&data_saved_lock, flags);
    data->state = STATE_NO_DATA;
    if (!cpu_isset(cpu, data->cpu_event)) {
        spin_unlock_irqrestore(&data_saved_lock, flags);
        return 0;
    }
    cpu_clear(cpu, data->cpu_event);
    if (data->saved_num) {
        shift1_data_saved(data, data->saved_num - 1);
        data->saved_num = 0;
    }
    spin_unlock_irqrestore(&data_saved_lock, flags);
    rh = (sal_log_record_header_t *)(data->log_buffer);
    /* Corrected errors have already been cleared from SAL */
    if (rh->severity != sal_log_severity_corrected)
        call_on_cpu(cpu, salinfo_log_clear_cpu, data);
    /* clearing a record may make a new record visible */
    salinfo_log_new_read(cpu, data);
    if (data->state == STATE_LOG_RECORD) {
        spin_lock_irqsave(&data_saved_lock, flags);
        cpu_set(cpu, data->cpu_event);
        salinfo_work_to_do(data);
        spin_unlock_irqrestore(&data_saved_lock, flags);
    }
    return 0;
}

static ssize_t
salinfo_log_write(struct file *file, const char __user *buffer, size_t count, loff_t *ppos)
{
    struct inode *inode = file->f_path.dentry->d_inode;
    struct proc_dir_entry *entry = PDE(inode);
    struct salinfo_data *data = entry->data;
    char cmd[32];
    size_t size;
    u32 offset;
    int cpu;

    size = sizeof(cmd);
    if (count < size)
        size = count;
    if (copy_from_user(cmd, buffer, size))
        return -EFAULT;

    if (sscanf(cmd, "read %d", &cpu) == 1) {
        salinfo_log_new_read(cpu, data);
    } else if (sscanf(cmd, "clear %d", &cpu) == 1) {
        int ret;
        if ((ret = salinfo_log_clear(data, cpu)))
            count = ret;
    } else if (sscanf(cmd, "oemdata %d %d", &cpu, &offset) == 2) {
        if (data->state != STATE_LOG_RECORD && data->state != STATE_OEMDATA)
            return -EINVAL;
        if (offset > data->log_size - sizeof(efi_guid_t))
            return -EINVAL;
        data->state = STATE_OEMDATA;
        if (salinfo_platform_oemdata) {
            struct salinfo_platform_oemdata_parms parms = {
                .efi_guid = data->log_buffer + offset,
                .oemdata = &data->oemdata,
                .oemdata_size = &data->oemdata_size
            };
            call_on_cpu(cpu, salinfo_platform_oemdata_cpu, &parms);
            if (parms.ret)
                count = parms.ret;
        } else
            data->oemdata_size = 0;
    } else
        return -EINVAL;

    return count;
}

static const struct file_operations salinfo_data_fops = {
    .open    = salinfo_log_open,
    .release = salinfo_log_release,
    .read    = salinfo_log_read,
    .write   = salinfo_log_write,
    .llseek  = default_llseek,
};

static int __cpuinit
salinfo_cpu_callback(struct notifier_block *nb, unsigned long action, void *hcpu)
{
    unsigned int i, cpu = (unsigned long)hcpu;
    unsigned long flags;
    struct salinfo_data *data;
    switch (action) {
    case CPU_ONLINE:
    case CPU_ONLINE_FROZEN:
        spin_lock_irqsave(&data_saved_lock, flags);
        for (i = 0, data = salinfo_data;
             i < ARRAY_SIZE(salinfo_data);
             ++i, ++data) {
            cpu_set(cpu, data->cpu_event);
            salinfo_work_to_do(data);
        }
        spin_unlock_irqrestore(&data_saved_lock, flags);
        break;
    case CPU_DEAD:
    case CPU_DEAD_FROZEN:
        spin_lock_irqsave(&data_saved_lock, flags);
        for (i = 0, data = salinfo_data;
             i < ARRAY_SIZE(salinfo_data);
             ++i, ++data) {
            struct salinfo_data_saved *data_saved;
            int j;
            for (j = ARRAY_SIZE(data->data_saved) - 1, data_saved = data->data_saved + j;
                 j >= 0;
                 --j, --data_saved) {
                if (data_saved->buffer && data_saved->cpu == cpu) {
                    shift1_data_saved(data, j);
                }
            }
            cpu_clear(cpu, data->cpu_event);
        }
        spin_unlock_irqrestore(&data_saved_lock, flags);
        break;
    }
    return NOTIFY_OK;
}

static struct notifier_block salinfo_cpu_notifier __cpuinitdata =
{
    .notifier_call = salinfo_cpu_callback,
    .priority = 0,
};

static int __init
salinfo_init(void)
{
    struct proc_dir_entry *salinfo_dir; /* /proc/sal dir entry */
    struct proc_dir_entry **sdir = salinfo_proc_entries; /* keeps track of every entry */
    struct proc_dir_entry *dir, *entry;
    struct salinfo_data *data;
    int i, j;

    salinfo_dir = proc_mkdir("sal", NULL);
    if (!salinfo_dir)
        return 0;

    for (i=0; i < NR_SALINFO_ENTRIES; i++) {
        /* pass the feature bit in question as misc data */
        *sdir++ = create_proc_read_entry (salinfo_entries[i].name, 0, salinfo_dir,
                          salinfo_read, (void *)salinfo_entries[i].feature);
    }

    for (i = 0; i < ARRAY_SIZE(salinfo_log_name); i++) {
        data = salinfo_data + i;
        data->type = i;
        sema_init(&data->mutex, 1);
        dir = proc_mkdir(salinfo_log_name[i], salinfo_dir);
        if (!dir)
            continue;

        entry = proc_create_data("event", S_IRUSR, dir,
                     &salinfo_event_fops, data);
        if (!entry)
            continue;
        *sdir++ = entry;

        entry = proc_create_data("data", S_IRUSR | S_IWUSR, dir,
                     &salinfo_data_fops, data);
        if (!entry)
            continue;
        *sdir++ = entry;

        /* we missed any events before now */
        for_each_online_cpu(j)
            cpu_set(j, data->cpu_event);

        *sdir++ = dir;
    }

    *sdir++ = salinfo_dir;

    init_timer(&salinfo_timer);
    salinfo_timer.expires = jiffies + SALINFO_TIMER_DELAY;
    salinfo_timer.function = &salinfo_timeout;
    add_timer(&salinfo_timer);

    register_hotcpu_notifier(&salinfo_cpu_notifier);

    return 0;
}

/*
 * 'data' contains an integer that corresponds to the feature we're
 * testing
 */
static int
salinfo_read(char *page, char **start, off_t off, int count, int *eof, void *data)
{
    int len = 0;

    len = sprintf(page, (sal_platform_features & (unsigned long)data) ? "1\n" : "0\n");

    if (len <= off+count) *eof = 1;

    *start = page + off;
    len   -= off;

    if (len>count) len = count;
    if (len<0) len = 0;

    return len;
}

module_init(salinfo_init);