pageattr-test.c

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/*
 * self test for change_page_attr.
 *
 * Clears the a test pte bit on random pages in the direct mapping,
 * then reverts and compares page tables forwards and afterwards.
 */
#include <linux/bootmem.h>
#include <linux/kthread.h>
#include <linux/random.h>
#include <linux/kernel.h>
#include <linux/init.h>
#include <linux/mm.h>

#include <asm/cacheflush.h>
#include <asm/pgtable.h>
#include <asm/kdebug.h>

/*
 * Only print the results of the first pass:
 */
static __read_mostly int print = 1;

enum {
    NTEST           = 400,
#ifdef CONFIG_X86_64
    LPS         = (1 << PMD_SHIFT),
#elif defined(CONFIG_X86_PAE)
    LPS         = (1 << PMD_SHIFT),
#else
    LPS         = (1 << 22),
#endif
    GPS         = (1<<30)
};

#define PAGE_CPA_TEST   __pgprot(_PAGE_CPA_TEST)

static int pte_testbit(pte_t pte)
{
    return pte_flags(pte) & _PAGE_UNUSED1;
}

struct split_state {
    long lpg, gpg, spg, exec;
    long min_exec, max_exec;
};

static int print_split(struct split_state *s)
{
    long i, expected, missed = 0;
    int err = 0;

    s->lpg = s->gpg = s->spg = s->exec = 0;
    s->min_exec = ~0UL;
    s->max_exec = 0;
    for (i = 0; i < max_pfn_mapped; ) {
        unsigned long addr = (unsigned long)__va(i << PAGE_SHIFT);
        unsigned int level;
        pte_t *pte;

        pte = lookup_address(addr, &level);
        if (!pte) {
            missed++;
            i++;
            continue;
        }

        if (level == PG_LEVEL_1G && sizeof(long) == 8) {
            s->gpg++;
            i += GPS/PAGE_SIZE;
        } else if (level == PG_LEVEL_2M) {
            if (!(pte_val(*pte) & _PAGE_PSE)) {
                printk(KERN_ERR
                    "%lx level %d but not PSE %Lx\n",
                    addr, level, (u64)pte_val(*pte));
                err = 1;
            }
            s->lpg++;
            i += LPS/PAGE_SIZE;
        } else {
            s->spg++;
            i++;
        }
        if (!(pte_val(*pte) & _PAGE_NX)) {
            s->exec++;
            if (addr < s->min_exec)
                s->min_exec = addr;
            if (addr > s->max_exec)
                s->max_exec = addr;
        }
    }
    if (print) {
        printk(KERN_INFO
            " 4k %lu large %lu gb %lu x %lu[%lx-%lx] miss %lu\n",
            s->spg, s->lpg, s->gpg, s->exec,
            s->min_exec != ~0UL ? s->min_exec : 0,
            s->max_exec, missed);
    }

    expected = (s->gpg*GPS + s->lpg*LPS)/PAGE_SIZE + s->spg + missed;
    if (expected != i) {
        printk(KERN_ERR "CPA max_pfn_mapped %lu but expected %lu\n",
            max_pfn_mapped, expected);
        return 1;
    }
    return err;
}

static unsigned long addr[NTEST];
static unsigned int len[NTEST];

/* Change the global bit on random pages in the direct mapping */
static int pageattr_test(void)
{
    struct split_state sa, sb, sc;
    unsigned long *bm;
    pte_t *pte, pte0;
    int failed = 0;
    unsigned int level;
    int i, k;
    int err;
    unsigned long test_addr;

    if (print)
        printk(KERN_INFO "CPA self-test:\n");

    bm = vzalloc((max_pfn_mapped + 7) / 8);
    if (!bm) {
        printk(KERN_ERR "CPA Cannot vmalloc bitmap\n");
        return -ENOMEM;
    }

    failed += print_split(&sa);
    srandom32(100);

    for (i = 0; i < NTEST; i++) {
        unsigned long pfn = random32() % max_pfn_mapped;

        addr[i] = (unsigned long)__va(pfn << PAGE_SHIFT);
        len[i] = random32() % 100;
        len[i] = min_t(unsigned long, len[i], max_pfn_mapped - pfn - 1);

        if (len[i] == 0)
            len[i] = 1;

        pte = NULL;
        pte0 = pfn_pte(0, __pgprot(0)); /* shut gcc up */

        for (k = 0; k < len[i]; k++) {
            pte = lookup_address(addr[i] + k*PAGE_SIZE, &level);
            if (!pte || pgprot_val(pte_pgprot(*pte)) == 0 ||
                !(pte_val(*pte) & _PAGE_PRESENT)) {
                addr[i] = 0;
                break;
            }
            if (k == 0) {
                pte0 = *pte;
            } else {
                if (pgprot_val(pte_pgprot(*pte)) !=
                    pgprot_val(pte_pgprot(pte0))) {
                    len[i] = k;
                    break;
                }
            }
            if (test_bit(pfn + k, bm)) {
                len[i] = k;
                break;
            }
            __set_bit(pfn + k, bm);
        }
        if (!addr[i] || !pte || !k) {
            addr[i] = 0;
            continue;
        }

        test_addr = addr[i];
        err = change_page_attr_set(&test_addr, len[i], PAGE_CPA_TEST, 0);
        if (err < 0) {
            printk(KERN_ERR "CPA %d failed %d\n", i, err);
            failed++;
        }

        pte = lookup_address(addr[i], &level);
        if (!pte || !pte_testbit(*pte) || pte_huge(*pte)) {
            printk(KERN_ERR "CPA %lx: bad pte %Lx\n", addr[i],
                pte ? (u64)pte_val(*pte) : 0ULL);
            failed++;
        }
        if (level != PG_LEVEL_4K) {
            printk(KERN_ERR "CPA %lx: unexpected level %d\n",
                addr[i], level);
            failed++;
        }

    }
    vfree(bm);

    failed += print_split(&sb);

    for (i = 0; i < NTEST; i++) {
        if (!addr[i])
            continue;
        pte = lookup_address(addr[i], &level);
        if (!pte) {
            printk(KERN_ERR "CPA lookup of %lx failed\n", addr[i]);
            failed++;
            continue;
        }
        test_addr = addr[i];
        err = change_page_attr_clear(&test_addr, len[i], PAGE_CPA_TEST, 0);
        if (err < 0) {
            printk(KERN_ERR "CPA reverting failed: %d\n", err);
            failed++;
        }
        pte = lookup_address(addr[i], &level);
        if (!pte || pte_testbit(*pte)) {
            printk(KERN_ERR "CPA %lx: bad pte after revert %Lx\n",
                addr[i], pte ? (u64)pte_val(*pte) : 0ULL);
            failed++;
        }

    }

    failed += print_split(&sc);

    if (failed) {
        WARN(1, KERN_ERR "NOT PASSED. Please report.\n");
        return -EINVAL;
    } else {
        if (print)
            printk(KERN_INFO "ok.\n");
    }

    return 0;
}

static int do_pageattr_test(void *__unused)
{
    while (!kthread_should_stop()) {
        schedule_timeout_interruptible(HZ*30);
        if (pageattr_test() < 0)
            break;
        if (print)
            print--;
    }
    return 0;
}

static int start_pageattr_test(void)
{
    struct task_struct *p;

    p = kthread_create(do_pageattr_test, NULL, "pageattr-test");
    if (!IS_ERR(p))
        wake_up_process(p);
    else
        WARN_ON(1);

    return 0;
}

module_init(start_pageattr_test);