280 lines
6.5 KiB
C
280 lines
6.5 KiB
C
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// SPDX-License-Identifier: GPL-2.0-only
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/*
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* KSM functional tests
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*
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* Copyright 2022, Red Hat, Inc.
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*
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* Author(s): David Hildenbrand <david@redhat.com>
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*/
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#define _GNU_SOURCE
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#include <stdlib.h>
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#include <string.h>
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#include <stdbool.h>
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#include <stdint.h>
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#include <unistd.h>
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#include <errno.h>
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#include <fcntl.h>
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#include <sys/mman.h>
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#include <sys/syscall.h>
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#include <sys/ioctl.h>
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#include <linux/userfaultfd.h>
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#include "../kselftest.h"
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#include "vm_util.h"
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#define KiB 1024u
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#define MiB (1024 * KiB)
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static int ksm_fd;
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static int ksm_full_scans_fd;
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static int pagemap_fd;
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static size_t pagesize;
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static bool range_maps_duplicates(char *addr, unsigned long size)
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{
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unsigned long offs_a, offs_b, pfn_a, pfn_b;
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/*
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* There is no easy way to check if there are KSM pages mapped into
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* this range. We only check that the range does not map the same PFN
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* twice by comparing each pair of mapped pages.
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*/
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for (offs_a = 0; offs_a < size; offs_a += pagesize) {
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pfn_a = pagemap_get_pfn(pagemap_fd, addr + offs_a);
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/* Page not present or PFN not exposed by the kernel. */
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if (pfn_a == -1ul || !pfn_a)
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continue;
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for (offs_b = offs_a + pagesize; offs_b < size;
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offs_b += pagesize) {
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pfn_b = pagemap_get_pfn(pagemap_fd, addr + offs_b);
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if (pfn_b == -1ul || !pfn_b)
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continue;
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if (pfn_a == pfn_b)
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return true;
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}
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}
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return false;
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}
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static long ksm_get_full_scans(void)
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{
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char buf[10];
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ssize_t ret;
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ret = pread(ksm_full_scans_fd, buf, sizeof(buf) - 1, 0);
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if (ret <= 0)
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return -errno;
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buf[ret] = 0;
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return strtol(buf, NULL, 10);
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}
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static int ksm_merge(void)
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{
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long start_scans, end_scans;
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/* Wait for two full scans such that any possible merging happened. */
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start_scans = ksm_get_full_scans();
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if (start_scans < 0)
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return start_scans;
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if (write(ksm_fd, "1", 1) != 1)
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return -errno;
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do {
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end_scans = ksm_get_full_scans();
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if (end_scans < 0)
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return end_scans;
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} while (end_scans < start_scans + 2);
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return 0;
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}
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static char *mmap_and_merge_range(char val, unsigned long size)
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{
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char *map;
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map = mmap(NULL, size, PROT_READ|PROT_WRITE,
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MAP_PRIVATE|MAP_ANON, -1, 0);
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if (map == MAP_FAILED) {
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ksft_test_result_fail("mmap() failed\n");
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return MAP_FAILED;
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}
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/* Don't use THP. Ignore if THP are not around on a kernel. */
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if (madvise(map, size, MADV_NOHUGEPAGE) && errno != EINVAL) {
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ksft_test_result_fail("MADV_NOHUGEPAGE failed\n");
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goto unmap;
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}
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/* Make sure each page contains the same values to merge them. */
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memset(map, val, size);
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if (madvise(map, size, MADV_MERGEABLE)) {
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ksft_test_result_fail("MADV_MERGEABLE failed\n");
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goto unmap;
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}
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/* Run KSM to trigger merging and wait. */
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if (ksm_merge()) {
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ksft_test_result_fail("Running KSM failed\n");
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goto unmap;
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}
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return map;
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unmap:
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munmap(map, size);
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return MAP_FAILED;
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}
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static void test_unmerge(void)
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{
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const unsigned int size = 2 * MiB;
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char *map;
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ksft_print_msg("[RUN] %s\n", __func__);
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map = mmap_and_merge_range(0xcf, size);
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if (map == MAP_FAILED)
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return;
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if (madvise(map, size, MADV_UNMERGEABLE)) {
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ksft_test_result_fail("MADV_UNMERGEABLE failed\n");
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goto unmap;
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}
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ksft_test_result(!range_maps_duplicates(map, size),
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"Pages were unmerged\n");
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unmap:
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munmap(map, size);
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}
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static void test_unmerge_discarded(void)
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{
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const unsigned int size = 2 * MiB;
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char *map;
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ksft_print_msg("[RUN] %s\n", __func__);
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map = mmap_and_merge_range(0xcf, size);
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if (map == MAP_FAILED)
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return;
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/* Discard half of all mapped pages so we have pte_none() entries. */
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if (madvise(map, size / 2, MADV_DONTNEED)) {
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ksft_test_result_fail("MADV_DONTNEED failed\n");
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goto unmap;
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}
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if (madvise(map, size, MADV_UNMERGEABLE)) {
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ksft_test_result_fail("MADV_UNMERGEABLE failed\n");
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goto unmap;
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}
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ksft_test_result(!range_maps_duplicates(map, size),
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"Pages were unmerged\n");
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unmap:
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munmap(map, size);
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}
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#ifdef __NR_userfaultfd
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static void test_unmerge_uffd_wp(void)
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{
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struct uffdio_writeprotect uffd_writeprotect;
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struct uffdio_register uffdio_register;
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const unsigned int size = 2 * MiB;
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struct uffdio_api uffdio_api;
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char *map;
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int uffd;
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ksft_print_msg("[RUN] %s\n", __func__);
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map = mmap_and_merge_range(0xcf, size);
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if (map == MAP_FAILED)
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return;
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/* See if UFFD is around. */
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uffd = syscall(__NR_userfaultfd, O_CLOEXEC | O_NONBLOCK);
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if (uffd < 0) {
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ksft_test_result_skip("__NR_userfaultfd failed\n");
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goto unmap;
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}
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/* See if UFFD-WP is around. */
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uffdio_api.api = UFFD_API;
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uffdio_api.features = UFFD_FEATURE_PAGEFAULT_FLAG_WP;
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if (ioctl(uffd, UFFDIO_API, &uffdio_api) < 0) {
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ksft_test_result_fail("UFFDIO_API failed\n");
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goto close_uffd;
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}
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if (!(uffdio_api.features & UFFD_FEATURE_PAGEFAULT_FLAG_WP)) {
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ksft_test_result_skip("UFFD_FEATURE_PAGEFAULT_FLAG_WP not available\n");
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goto close_uffd;
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}
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/* Register UFFD-WP, no need for an actual handler. */
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uffdio_register.range.start = (unsigned long) map;
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uffdio_register.range.len = size;
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uffdio_register.mode = UFFDIO_REGISTER_MODE_WP;
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if (ioctl(uffd, UFFDIO_REGISTER, &uffdio_register) < 0) {
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ksft_test_result_fail("UFFDIO_REGISTER_MODE_WP failed\n");
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goto close_uffd;
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}
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/* Write-protect the range using UFFD-WP. */
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uffd_writeprotect.range.start = (unsigned long) map;
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uffd_writeprotect.range.len = size;
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uffd_writeprotect.mode = UFFDIO_WRITEPROTECT_MODE_WP;
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if (ioctl(uffd, UFFDIO_WRITEPROTECT, &uffd_writeprotect)) {
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ksft_test_result_fail("UFFDIO_WRITEPROTECT failed\n");
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goto close_uffd;
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}
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if (madvise(map, size, MADV_UNMERGEABLE)) {
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ksft_test_result_fail("MADV_UNMERGEABLE failed\n");
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goto close_uffd;
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}
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ksft_test_result(!range_maps_duplicates(map, size),
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"Pages were unmerged\n");
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close_uffd:
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close(uffd);
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unmap:
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munmap(map, size);
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}
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#endif
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int main(int argc, char **argv)
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{
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unsigned int tests = 2;
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int err;
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#ifdef __NR_userfaultfd
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tests++;
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#endif
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ksft_print_header();
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ksft_set_plan(tests);
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pagesize = getpagesize();
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ksm_fd = open("/sys/kernel/mm/ksm/run", O_RDWR);
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if (ksm_fd < 0)
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ksft_exit_skip("open(\"/sys/kernel/mm/ksm/run\") failed\n");
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ksm_full_scans_fd = open("/sys/kernel/mm/ksm/full_scans", O_RDONLY);
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if (ksm_full_scans_fd < 0)
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ksft_exit_skip("open(\"/sys/kernel/mm/ksm/full_scans\") failed\n");
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pagemap_fd = open("/proc/self/pagemap", O_RDONLY);
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if (pagemap_fd < 0)
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ksft_exit_skip("open(\"/proc/self/pagemap\") failed\n");
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test_unmerge();
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test_unmerge_discarded();
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#ifdef __NR_userfaultfd
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test_unmerge_uffd_wp();
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#endif
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err = ksft_get_fail_cnt();
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if (err)
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ksft_exit_fail_msg("%d out of %d tests failed\n",
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err, ksft_test_num());
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return ksft_exit_pass();
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}
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