crash.c

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/*
 * arch/ia64/kernel/crash.c
 *
 * Architecture specific (ia64) functions for kexec based crash dumps.
 *
 * Created by: Khalid Aziz <[email protected]>
 * Copyright (C) 2005 Hewlett-Packard Development Company, L.P.
 * Copyright (C) 2005 Intel Corp    Zou Nan hai <[email protected]>
 *
 */
#include <linux/smp.h>
#include <linux/delay.h>
#include <linux/crash_dump.h>
#include <linux/bootmem.h>
#include <linux/kexec.h>
#include <linux/elfcore.h>
#include <linux/sysctl.h>
#include <linux/init.h>
#include <linux/kdebug.h>

#include <asm/mca.h>

int kdump_status[NR_CPUS];
static atomic_t kdump_cpu_frozen;
atomic_t kdump_in_progress;
static int kdump_freeze_monarch;
static int kdump_on_init = 1;
static int kdump_on_fatal_mca = 1;

static inline Elf64_Word
*append_elf_note(Elf64_Word *buf, char *name, unsigned type, void *data,
        size_t data_len)
{
    struct elf_note *note = (struct elf_note *)buf;
    note->n_namesz = strlen(name) + 1;
    note->n_descsz = data_len;
    note->n_type   = type;
    buf += (sizeof(*note) + 3)/4;
    memcpy(buf, name, note->n_namesz);
    buf += (note->n_namesz + 3)/4;
    memcpy(buf, data, data_len);
    buf += (data_len + 3)/4;
    return buf;
}

static void
final_note(void *buf)
{
    memset(buf, 0, sizeof(struct elf_note));
}

extern void ia64_dump_cpu_regs(void *);

static DEFINE_PER_CPU(struct elf_prstatus, elf_prstatus);

void
crash_save_this_cpu(void)
{
    void *buf;
    unsigned long cfm, sof, sol;

    int cpu = smp_processor_id();
    struct elf_prstatus *prstatus = &per_cpu(elf_prstatus, cpu);

    elf_greg_t *dst = (elf_greg_t *)&(prstatus->pr_reg);
    memset(prstatus, 0, sizeof(*prstatus));
    prstatus->pr_pid = current->pid;

    ia64_dump_cpu_regs(dst);
    cfm = dst[43];
    sol = (cfm >> 7) & 0x7f;
    sof = cfm & 0x7f;
    dst[46] = (unsigned long)ia64_rse_skip_regs((unsigned long *)dst[46],
            sof - sol);

    buf = (u64 *) per_cpu_ptr(crash_notes, cpu);
    if (!buf)
        return;
    buf = append_elf_note(buf, KEXEC_CORE_NOTE_NAME, NT_PRSTATUS, prstatus,
            sizeof(*prstatus));
    final_note(buf);
}

#ifdef CONFIG_SMP
static int
kdump_wait_cpu_freeze(void)
{
    int cpu_num = num_online_cpus() - 1;
    int timeout = 1000;
    while(timeout-- > 0) {
        if (atomic_read(&kdump_cpu_frozen) == cpu_num)
            return 0;
        udelay(1000);
    }
    return 1;
}
#endif

void
machine_crash_shutdown(struct pt_regs *pt)
{
    /* This function is only called after the system
     * has paniced or is otherwise in a critical state.
     * The minimum amount of code to allow a kexec'd kernel
     * to run successfully needs to happen here.
     *
     * In practice this means shooting down the other cpus in
     * an SMP system.
     */
    kexec_disable_iosapic();
#ifdef CONFIG_SMP
    /*
     * If kdump_on_init is set and an INIT is asserted here, kdump will
     * be started again via INIT monarch.
     */
    local_irq_disable();
    ia64_set_psr_mc();  /* mask MCA/INIT */
    if (atomic_inc_return(&kdump_in_progress) != 1)
        unw_init_running(kdump_cpu_freeze, NULL);

    /*
     * Now this cpu is ready for kdump.
     * Stop all others by IPI or INIT.  They could receive INIT from
     * outside and might be INIT monarch, but only thing they have to
     * do is falling into kdump_cpu_freeze().
     *
     * If an INIT is asserted here:
     * - All receivers might be slaves, since some of cpus could already
     *   be frozen and INIT might be masked on monarch.  In this case,
     *   all slaves will be frozen soon since kdump_in_progress will let
     *   them into DIE_INIT_SLAVE_LEAVE.
     * - One might be a monarch, but INIT rendezvous will fail since
     *   at least this cpu already have INIT masked so it never join
     *   to the rendezvous.  In this case, all slaves and monarch will
     *   be frozen soon with no wait since the INIT rendezvous is skipped
     *   by kdump_in_progress.
     */
    kdump_smp_send_stop();
    /* not all cpu response to IPI, send INIT to freeze them */
    if (kdump_wait_cpu_freeze()) {
        kdump_smp_send_init();
        /* wait again, don't go ahead if possible */
        kdump_wait_cpu_freeze();
    }
#endif
}

static void
machine_kdump_on_init(void)
{
    crash_save_vmcoreinfo();
    local_irq_disable();
    kexec_disable_iosapic();
    machine_kexec(ia64_kimage);
}

void
kdump_cpu_freeze(struct unw_frame_info *info, void *arg)
{
    int cpuid;

    local_irq_disable();
    cpuid = smp_processor_id();
    crash_save_this_cpu();
    current->thread.ksp = (__u64)info->sw - 16;

    ia64_set_psr_mc();  /* mask MCA/INIT and stop reentrance */

    atomic_inc(&kdump_cpu_frozen);
    kdump_status[cpuid] = 1;
    mb();
    for (;;)
        cpu_relax();
}

static int
kdump_init_notifier(struct notifier_block *self, unsigned long val, void *data)
{
    struct ia64_mca_notify_die *nd;
    struct die_args *args = data;

    if (atomic_read(&kdump_in_progress)) {
        switch (val) {
        case DIE_INIT_MONARCH_LEAVE:
            if (!kdump_freeze_monarch)
                break;
            /* fall through */
        case DIE_INIT_SLAVE_LEAVE:
        case DIE_INIT_MONARCH_ENTER:
        case DIE_MCA_RENDZVOUS_LEAVE:
            unw_init_running(kdump_cpu_freeze, NULL);
            break;
        }
    }

    if (!kdump_on_init && !kdump_on_fatal_mca)
        return NOTIFY_DONE;

    if (!ia64_kimage) {
        if (val == DIE_INIT_MONARCH_LEAVE)
            ia64_mca_printk(KERN_NOTICE
                    "%s: kdump not configured\n",
                    __func__);
        return NOTIFY_DONE;
    }

    if (val != DIE_INIT_MONARCH_LEAVE &&
        val != DIE_INIT_MONARCH_PROCESS &&
        val != DIE_MCA_MONARCH_LEAVE)
        return NOTIFY_DONE;

    nd = (struct ia64_mca_notify_die *)args->err;

    switch (val) {
    case DIE_INIT_MONARCH_PROCESS:
        /* Reason code 1 means machine check rendezvous*/
        if (kdump_on_init && (nd->sos->rv_rc != 1)) {
            if (atomic_inc_return(&kdump_in_progress) != 1)
                kdump_freeze_monarch = 1;
        }
        break;
    case DIE_INIT_MONARCH_LEAVE:
        /* Reason code 1 means machine check rendezvous*/
        if (kdump_on_init && (nd->sos->rv_rc != 1))
            machine_kdump_on_init();
        break;
    case DIE_MCA_MONARCH_LEAVE:
        /* *(nd->data) indicate if MCA is recoverable */
        if (kdump_on_fatal_mca && !(*(nd->data))) {
            if (atomic_inc_return(&kdump_in_progress) == 1)
                machine_kdump_on_init();
            /* We got fatal MCA while kdump!? No way!! */
        }
        break;
    }
    return NOTIFY_DONE;
}

#ifdef CONFIG_SYSCTL
static ctl_table kdump_ctl_table[] = {
    {
        .procname = "kdump_on_init",
        .data = &kdump_on_init,
        .maxlen = sizeof(int),
        .mode = 0644,
        .proc_handler = proc_dointvec,
    },
    {
        .procname = "kdump_on_fatal_mca",
        .data = &kdump_on_fatal_mca,
        .maxlen = sizeof(int),
        .mode = 0644,
        .proc_handler = proc_dointvec,
    },
    { }
};

static ctl_table sys_table[] = {
    {
      .procname = "kernel",
      .mode = 0555,
      .child = kdump_ctl_table,
    },
    { }
};
#endif

static int
machine_crash_setup(void)
{
    /* be notified before default_monarch_init_process */
    static struct notifier_block kdump_init_notifier_nb = {
        .notifier_call = kdump_init_notifier,
        .priority = 1,
    };
    int ret;
    if((ret = register_die_notifier(&kdump_init_notifier_nb)) != 0)
        return ret;
#ifdef CONFIG_SYSCTL
    register_sysctl_table(sys_table);
#endif
    return 0;
}

__initcall(machine_crash_setup);