nmi_selftest.c

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/*
 * arch/x86/kernel/nmi-selftest.c
 *
 * Testsuite for NMI: IPIs
 *
 * Started by Don Zickus:
 * (using lib/locking-selftest.c as a guide)
 *
 *   Copyright (C) 2011 Red Hat, Inc., Don Zickus <[email protected]>
 */

#include <linux/smp.h>
#include <linux/cpumask.h>
#include <linux/delay.h>
#include <linux/init.h>
#include <linux/percpu.h>

#include <asm/apic.h>
#include <asm/nmi.h>

#define SUCCESS     0
#define FAILURE     1
#define TIMEOUT     2

static int __initdata nmi_fail;

/* check to see if NMI IPIs work on this machine */
static DECLARE_BITMAP(nmi_ipi_mask, NR_CPUS) __initdata;

static int __initdata testcase_total;
static int __initdata testcase_successes;
static int __initdata expected_testcase_failures;
static int __initdata unexpected_testcase_failures;
static int __initdata unexpected_testcase_unknowns;

static int __init nmi_unk_cb(unsigned int val, struct pt_regs *regs)
{
    unexpected_testcase_unknowns++;
    return NMI_HANDLED;
}

static void __init init_nmi_testsuite(void)
{
    /* trap all the unknown NMIs we may generate */
    register_nmi_handler(NMI_UNKNOWN, nmi_unk_cb, 0, "nmi_selftest_unk",
            __initdata);
}

static void __init cleanup_nmi_testsuite(void)
{
    unregister_nmi_handler(NMI_UNKNOWN, "nmi_selftest_unk");
}

static int __init test_nmi_ipi_callback(unsigned int val, struct pt_regs *regs)
{
        int cpu = raw_smp_processor_id();

        if (cpumask_test_and_clear_cpu(cpu, to_cpumask(nmi_ipi_mask)))
                return NMI_HANDLED;

        return NMI_DONE;
}

static void __init test_nmi_ipi(struct cpumask *mask)
{
    unsigned long timeout;

    if (register_nmi_handler(NMI_LOCAL, test_nmi_ipi_callback,
                 NMI_FLAG_FIRST, "nmi_selftest", __initdata)) {
        nmi_fail = FAILURE;
        return;
    }

    /* sync above data before sending NMI */
    wmb();

    apic->send_IPI_mask(mask, NMI_VECTOR);

    /* Don't wait longer than a second */
    timeout = USEC_PER_SEC;
    while (!cpumask_empty(mask) && timeout--)
            udelay(1);

    /* What happens if we timeout, do we still unregister?? */
    unregister_nmi_handler(NMI_LOCAL, "nmi_selftest");

    if (!timeout)
        nmi_fail = TIMEOUT;
    return;
}

static void __init remote_ipi(void)
{
    cpumask_copy(to_cpumask(nmi_ipi_mask), cpu_online_mask);
    cpumask_clear_cpu(smp_processor_id(), to_cpumask(nmi_ipi_mask));
    if (!cpumask_empty(to_cpumask(nmi_ipi_mask)))
        test_nmi_ipi(to_cpumask(nmi_ipi_mask));
}

static void __init local_ipi(void)
{
    cpumask_clear(to_cpumask(nmi_ipi_mask));
    cpumask_set_cpu(smp_processor_id(), to_cpumask(nmi_ipi_mask));
    test_nmi_ipi(to_cpumask(nmi_ipi_mask));
}

static void __init reset_nmi(void)
{
    nmi_fail = 0;
}

static void __init dotest(void (*testcase_fn)(void), int expected)
{
    testcase_fn();
    /*
     * Filter out expected failures:
     */
    if (nmi_fail != expected) {
        unexpected_testcase_failures++;

        if (nmi_fail == FAILURE)
            printk(KERN_CONT "FAILED |");
        else if (nmi_fail == TIMEOUT)
            printk(KERN_CONT "TIMEOUT|");
        else
            printk(KERN_CONT "ERROR  |");
        dump_stack();
    } else {
        testcase_successes++;
        printk(KERN_CONT "  ok  |");
    }
    testcase_total++;

    reset_nmi();
}

static inline void __init print_testname(const char *testname)
{
    printk("%12s:", testname);
}

void __init nmi_selftest(void)
{
    init_nmi_testsuite();

        /*
     * Run the testsuite:
     */
    printk("----------------\n");
    printk("| NMI testsuite:\n");
    printk("--------------------\n");

    print_testname("remote IPI");
    dotest(remote_ipi, SUCCESS);
    printk(KERN_CONT "\n");
    print_testname("local IPI");
    dotest(local_ipi, SUCCESS);
    printk(KERN_CONT "\n");

    cleanup_nmi_testsuite();

    if (unexpected_testcase_failures) {
        printk("--------------------\n");
        printk("BUG: %3d unexpected failures (out of %3d) - debugging disabled! |\n",
            unexpected_testcase_failures, testcase_total);
        printk("-----------------------------------------------------------------\n");
    } else if (expected_testcase_failures && testcase_successes) {
        printk("--------------------\n");
        printk("%3d out of %3d testcases failed, as expected. |\n",
            expected_testcase_failures, testcase_total);
        printk("----------------------------------------------------\n");
    } else if (expected_testcase_failures && !testcase_successes) {
        printk("--------------------\n");
        printk("All %3d testcases failed, as expected. |\n",
            expected_testcase_failures);
        printk("----------------------------------------\n");
    } else {
        printk("--------------------\n");
        printk("Good, all %3d testcases passed! |\n",
            testcase_successes);
        printk("---------------------------------\n");
    }
}