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-rw-r--r--tools/testing/selftests/mm/cow.c1712
1 files changed, 1712 insertions, 0 deletions
diff --git a/tools/testing/selftests/mm/cow.c b/tools/testing/selftests/mm/cow.c
new file mode 100644
index 0000000000..6f2f839904
--- /dev/null
+++ b/tools/testing/selftests/mm/cow.c
@@ -0,0 +1,1712 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * COW (Copy On Write) tests.
+ *
+ * Copyright 2022, Red Hat, Inc.
+ *
+ * Author(s): David Hildenbrand <david@redhat.com>
+ */
+#define _GNU_SOURCE
+#include <stdlib.h>
+#include <string.h>
+#include <stdbool.h>
+#include <stdint.h>
+#include <unistd.h>
+#include <errno.h>
+#include <fcntl.h>
+#include <assert.h>
+#include <linux/mman.h>
+#include <sys/mman.h>
+#include <sys/ioctl.h>
+#include <sys/wait.h>
+#include <linux/memfd.h>
+
+#include "local_config.h"
+#ifdef LOCAL_CONFIG_HAVE_LIBURING
+#include <liburing.h>
+#endif /* LOCAL_CONFIG_HAVE_LIBURING */
+
+#include "../../../../mm/gup_test.h"
+#include "../kselftest.h"
+#include "vm_util.h"
+
+static size_t pagesize;
+static int pagemap_fd;
+static size_t thpsize;
+static int nr_hugetlbsizes;
+static size_t hugetlbsizes[10];
+static int gup_fd;
+static bool has_huge_zeropage;
+
+static void detect_huge_zeropage(void)
+{
+ int fd = open("/sys/kernel/mm/transparent_hugepage/use_zero_page",
+ O_RDONLY);
+ size_t enabled = 0;
+ char buf[15];
+ int ret;
+
+ if (fd < 0)
+ return;
+
+ ret = pread(fd, buf, sizeof(buf), 0);
+ if (ret > 0 && ret < sizeof(buf)) {
+ buf[ret] = 0;
+
+ enabled = strtoul(buf, NULL, 10);
+ if (enabled == 1) {
+ has_huge_zeropage = true;
+ ksft_print_msg("[INFO] huge zeropage is enabled\n");
+ }
+ }
+
+ close(fd);
+}
+
+static bool range_is_swapped(void *addr, size_t size)
+{
+ for (; size; addr += pagesize, size -= pagesize)
+ if (!pagemap_is_swapped(pagemap_fd, addr))
+ return false;
+ return true;
+}
+
+struct comm_pipes {
+ int child_ready[2];
+ int parent_ready[2];
+};
+
+static int setup_comm_pipes(struct comm_pipes *comm_pipes)
+{
+ if (pipe(comm_pipes->child_ready) < 0)
+ return -errno;
+ if (pipe(comm_pipes->parent_ready) < 0) {
+ close(comm_pipes->child_ready[0]);
+ close(comm_pipes->child_ready[1]);
+ return -errno;
+ }
+
+ return 0;
+}
+
+static void close_comm_pipes(struct comm_pipes *comm_pipes)
+{
+ close(comm_pipes->child_ready[0]);
+ close(comm_pipes->child_ready[1]);
+ close(comm_pipes->parent_ready[0]);
+ close(comm_pipes->parent_ready[1]);
+}
+
+static int child_memcmp_fn(char *mem, size_t size,
+ struct comm_pipes *comm_pipes)
+{
+ char *old = malloc(size);
+ char buf;
+
+ /* Backup the original content. */
+ memcpy(old, mem, size);
+
+ /* Wait until the parent modified the page. */
+ write(comm_pipes->child_ready[1], "0", 1);
+ while (read(comm_pipes->parent_ready[0], &buf, 1) != 1)
+ ;
+
+ /* See if we still read the old values. */
+ return memcmp(old, mem, size);
+}
+
+static int child_vmsplice_memcmp_fn(char *mem, size_t size,
+ struct comm_pipes *comm_pipes)
+{
+ struct iovec iov = {
+ .iov_base = mem,
+ .iov_len = size,
+ };
+ ssize_t cur, total, transferred;
+ char *old, *new;
+ int fds[2];
+ char buf;
+
+ old = malloc(size);
+ new = malloc(size);
+
+ /* Backup the original content. */
+ memcpy(old, mem, size);
+
+ if (pipe(fds) < 0)
+ return -errno;
+
+ /* Trigger a read-only pin. */
+ transferred = vmsplice(fds[1], &iov, 1, 0);
+ if (transferred < 0)
+ return -errno;
+ if (transferred == 0)
+ return -EINVAL;
+
+ /* Unmap it from our page tables. */
+ if (munmap(mem, size) < 0)
+ return -errno;
+
+ /* Wait until the parent modified it. */
+ write(comm_pipes->child_ready[1], "0", 1);
+ while (read(comm_pipes->parent_ready[0], &buf, 1) != 1)
+ ;
+
+ /* See if we still read the old values via the pipe. */
+ for (total = 0; total < transferred; total += cur) {
+ cur = read(fds[0], new + total, transferred - total);
+ if (cur < 0)
+ return -errno;
+ }
+
+ return memcmp(old, new, transferred);
+}
+
+typedef int (*child_fn)(char *mem, size_t size, struct comm_pipes *comm_pipes);
+
+static void do_test_cow_in_parent(char *mem, size_t size, bool do_mprotect,
+ child_fn fn)
+{
+ struct comm_pipes comm_pipes;
+ char buf;
+ int ret;
+
+ ret = setup_comm_pipes(&comm_pipes);
+ if (ret) {
+ ksft_test_result_fail("pipe() failed\n");
+ return;
+ }
+
+ ret = fork();
+ if (ret < 0) {
+ ksft_test_result_fail("fork() failed\n");
+ goto close_comm_pipes;
+ } else if (!ret) {
+ exit(fn(mem, size, &comm_pipes));
+ }
+
+ while (read(comm_pipes.child_ready[0], &buf, 1) != 1)
+ ;
+
+ if (do_mprotect) {
+ /*
+ * mprotect() optimizations might try avoiding
+ * write-faults by directly mapping pages writable.
+ */
+ ret = mprotect(mem, size, PROT_READ);
+ ret |= mprotect(mem, size, PROT_READ|PROT_WRITE);
+ if (ret) {
+ ksft_test_result_fail("mprotect() failed\n");
+ write(comm_pipes.parent_ready[1], "0", 1);
+ wait(&ret);
+ goto close_comm_pipes;
+ }
+ }
+
+ /* Modify the page. */
+ memset(mem, 0xff, size);
+ write(comm_pipes.parent_ready[1], "0", 1);
+
+ wait(&ret);
+ if (WIFEXITED(ret))
+ ret = WEXITSTATUS(ret);
+ else
+ ret = -EINVAL;
+
+ ksft_test_result(!ret, "No leak from parent into child\n");
+close_comm_pipes:
+ close_comm_pipes(&comm_pipes);
+}
+
+static void test_cow_in_parent(char *mem, size_t size)
+{
+ do_test_cow_in_parent(mem, size, false, child_memcmp_fn);
+}
+
+static void test_cow_in_parent_mprotect(char *mem, size_t size)
+{
+ do_test_cow_in_parent(mem, size, true, child_memcmp_fn);
+}
+
+static void test_vmsplice_in_child(char *mem, size_t size)
+{
+ do_test_cow_in_parent(mem, size, false, child_vmsplice_memcmp_fn);
+}
+
+static void test_vmsplice_in_child_mprotect(char *mem, size_t size)
+{
+ do_test_cow_in_parent(mem, size, true, child_vmsplice_memcmp_fn);
+}
+
+static void do_test_vmsplice_in_parent(char *mem, size_t size,
+ bool before_fork)
+{
+ struct iovec iov = {
+ .iov_base = mem,
+ .iov_len = size,
+ };
+ ssize_t cur, total, transferred;
+ struct comm_pipes comm_pipes;
+ char *old, *new;
+ int ret, fds[2];
+ char buf;
+
+ old = malloc(size);
+ new = malloc(size);
+
+ memcpy(old, mem, size);
+
+ ret = setup_comm_pipes(&comm_pipes);
+ if (ret) {
+ ksft_test_result_fail("pipe() failed\n");
+ goto free;
+ }
+
+ if (pipe(fds) < 0) {
+ ksft_test_result_fail("pipe() failed\n");
+ goto close_comm_pipes;
+ }
+
+ if (before_fork) {
+ transferred = vmsplice(fds[1], &iov, 1, 0);
+ if (transferred <= 0) {
+ ksft_test_result_fail("vmsplice() failed\n");
+ goto close_pipe;
+ }
+ }
+
+ ret = fork();
+ if (ret < 0) {
+ ksft_test_result_fail("fork() failed\n");
+ goto close_pipe;
+ } else if (!ret) {
+ write(comm_pipes.child_ready[1], "0", 1);
+ while (read(comm_pipes.parent_ready[0], &buf, 1) != 1)
+ ;
+ /* Modify page content in the child. */
+ memset(mem, 0xff, size);
+ exit(0);
+ }
+
+ if (!before_fork) {
+ transferred = vmsplice(fds[1], &iov, 1, 0);
+ if (transferred <= 0) {
+ ksft_test_result_fail("vmsplice() failed\n");
+ wait(&ret);
+ goto close_pipe;
+ }
+ }
+
+ while (read(comm_pipes.child_ready[0], &buf, 1) != 1)
+ ;
+ if (munmap(mem, size) < 0) {
+ ksft_test_result_fail("munmap() failed\n");
+ goto close_pipe;
+ }
+ write(comm_pipes.parent_ready[1], "0", 1);
+
+ /* Wait until the child is done writing. */
+ wait(&ret);
+ if (!WIFEXITED(ret)) {
+ ksft_test_result_fail("wait() failed\n");
+ goto close_pipe;
+ }
+
+ /* See if we still read the old values. */
+ for (total = 0; total < transferred; total += cur) {
+ cur = read(fds[0], new + total, transferred - total);
+ if (cur < 0) {
+ ksft_test_result_fail("read() failed\n");
+ goto close_pipe;
+ }
+ }
+
+ ksft_test_result(!memcmp(old, new, transferred),
+ "No leak from child into parent\n");
+close_pipe:
+ close(fds[0]);
+ close(fds[1]);
+close_comm_pipes:
+ close_comm_pipes(&comm_pipes);
+free:
+ free(old);
+ free(new);
+}
+
+static void test_vmsplice_before_fork(char *mem, size_t size)
+{
+ do_test_vmsplice_in_parent(mem, size, true);
+}
+
+static void test_vmsplice_after_fork(char *mem, size_t size)
+{
+ do_test_vmsplice_in_parent(mem, size, false);
+}
+
+#ifdef LOCAL_CONFIG_HAVE_LIBURING
+static void do_test_iouring(char *mem, size_t size, bool use_fork)
+{
+ struct comm_pipes comm_pipes;
+ struct io_uring_cqe *cqe;
+ struct io_uring_sqe *sqe;
+ struct io_uring ring;
+ ssize_t cur, total;
+ struct iovec iov;
+ char *buf, *tmp;
+ int ret, fd;
+ FILE *file;
+
+ ret = setup_comm_pipes(&comm_pipes);
+ if (ret) {
+ ksft_test_result_fail("pipe() failed\n");
+ return;
+ }
+
+ file = tmpfile();
+ if (!file) {
+ ksft_test_result_fail("tmpfile() failed\n");
+ goto close_comm_pipes;
+ }
+ fd = fileno(file);
+ assert(fd);
+
+ tmp = malloc(size);
+ if (!tmp) {
+ ksft_test_result_fail("malloc() failed\n");
+ goto close_file;
+ }
+
+ /* Skip on errors, as we might just lack kernel support. */
+ ret = io_uring_queue_init(1, &ring, 0);
+ if (ret < 0) {
+ ksft_test_result_skip("io_uring_queue_init() failed\n");
+ goto free_tmp;
+ }
+
+ /*
+ * Register the range as a fixed buffer. This will FOLL_WRITE | FOLL_PIN
+ * | FOLL_LONGTERM the range.
+ *
+ * Skip on errors, as we might just lack kernel support or might not
+ * have sufficient MEMLOCK permissions.
+ */
+ iov.iov_base = mem;
+ iov.iov_len = size;
+ ret = io_uring_register_buffers(&ring, &iov, 1);
+ if (ret) {
+ ksft_test_result_skip("io_uring_register_buffers() failed\n");
+ goto queue_exit;
+ }
+
+ if (use_fork) {
+ /*
+ * fork() and keep the child alive until we're done. Note that
+ * we expect the pinned page to not get shared with the child.
+ */
+ ret = fork();
+ if (ret < 0) {
+ ksft_test_result_fail("fork() failed\n");
+ goto unregister_buffers;
+ } else if (!ret) {
+ write(comm_pipes.child_ready[1], "0", 1);
+ while (read(comm_pipes.parent_ready[0], &buf, 1) != 1)
+ ;
+ exit(0);
+ }
+
+ while (read(comm_pipes.child_ready[0], &buf, 1) != 1)
+ ;
+ } else {
+ /*
+ * Map the page R/O into the page table. Enable softdirty
+ * tracking to stop the page from getting mapped R/W immediately
+ * again by mprotect() optimizations. Note that we don't have an
+ * easy way to test if that worked (the pagemap does not export
+ * if the page is mapped R/O vs. R/W).
+ */
+ ret = mprotect(mem, size, PROT_READ);
+ clear_softdirty();
+ ret |= mprotect(mem, size, PROT_READ | PROT_WRITE);
+ if (ret) {
+ ksft_test_result_fail("mprotect() failed\n");
+ goto unregister_buffers;
+ }
+ }
+
+ /*
+ * Modify the page and write page content as observed by the fixed
+ * buffer pin to the file so we can verify it.
+ */
+ memset(mem, 0xff, size);
+ sqe = io_uring_get_sqe(&ring);
+ if (!sqe) {
+ ksft_test_result_fail("io_uring_get_sqe() failed\n");
+ goto quit_child;
+ }
+ io_uring_prep_write_fixed(sqe, fd, mem, size, 0, 0);
+
+ ret = io_uring_submit(&ring);
+ if (ret < 0) {
+ ksft_test_result_fail("io_uring_submit() failed\n");
+ goto quit_child;
+ }
+
+ ret = io_uring_wait_cqe(&ring, &cqe);
+ if (ret < 0) {
+ ksft_test_result_fail("io_uring_wait_cqe() failed\n");
+ goto quit_child;
+ }
+
+ if (cqe->res != size) {
+ ksft_test_result_fail("write_fixed failed\n");
+ goto quit_child;
+ }
+ io_uring_cqe_seen(&ring, cqe);
+
+ /* Read back the file content to the temporary buffer. */
+ total = 0;
+ while (total < size) {
+ cur = pread(fd, tmp + total, size - total, total);
+ if (cur < 0) {
+ ksft_test_result_fail("pread() failed\n");
+ goto quit_child;
+ }
+ total += cur;
+ }
+
+ /* Finally, check if we read what we expected. */
+ ksft_test_result(!memcmp(mem, tmp, size),
+ "Longterm R/W pin is reliable\n");
+
+quit_child:
+ if (use_fork) {
+ write(comm_pipes.parent_ready[1], "0", 1);
+ wait(&ret);
+ }
+unregister_buffers:
+ io_uring_unregister_buffers(&ring);
+queue_exit:
+ io_uring_queue_exit(&ring);
+free_tmp:
+ free(tmp);
+close_file:
+ fclose(file);
+close_comm_pipes:
+ close_comm_pipes(&comm_pipes);
+}
+
+static void test_iouring_ro(char *mem, size_t size)
+{
+ do_test_iouring(mem, size, false);
+}
+
+static void test_iouring_fork(char *mem, size_t size)
+{
+ do_test_iouring(mem, size, true);
+}
+
+#endif /* LOCAL_CONFIG_HAVE_LIBURING */
+
+enum ro_pin_test {
+ RO_PIN_TEST,
+ RO_PIN_TEST_SHARED,
+ RO_PIN_TEST_PREVIOUSLY_SHARED,
+ RO_PIN_TEST_RO_EXCLUSIVE,
+};
+
+static void do_test_ro_pin(char *mem, size_t size, enum ro_pin_test test,
+ bool fast)
+{
+ struct pin_longterm_test args;
+ struct comm_pipes comm_pipes;
+ char *tmp, buf;
+ __u64 tmp_val;
+ int ret;
+
+ if (gup_fd < 0) {
+ ksft_test_result_skip("gup_test not available\n");
+ return;
+ }
+
+ tmp = malloc(size);
+ if (!tmp) {
+ ksft_test_result_fail("malloc() failed\n");
+ return;
+ }
+
+ ret = setup_comm_pipes(&comm_pipes);
+ if (ret) {
+ ksft_test_result_fail("pipe() failed\n");
+ goto free_tmp;
+ }
+
+ switch (test) {
+ case RO_PIN_TEST:
+ break;
+ case RO_PIN_TEST_SHARED:
+ case RO_PIN_TEST_PREVIOUSLY_SHARED:
+ /*
+ * Share the pages with our child. As the pages are not pinned,
+ * this should just work.
+ */
+ ret = fork();
+ if (ret < 0) {
+ ksft_test_result_fail("fork() failed\n");
+ goto close_comm_pipes;
+ } else if (!ret) {
+ write(comm_pipes.child_ready[1], "0", 1);
+ while (read(comm_pipes.parent_ready[0], &buf, 1) != 1)
+ ;
+ exit(0);
+ }
+
+ /* Wait until our child is ready. */
+ while (read(comm_pipes.child_ready[0], &buf, 1) != 1)
+ ;
+
+ if (test == RO_PIN_TEST_PREVIOUSLY_SHARED) {
+ /*
+ * Tell the child to quit now and wait until it quit.
+ * The pages should now be mapped R/O into our page
+ * tables, but they are no longer shared.
+ */
+ write(comm_pipes.parent_ready[1], "0", 1);
+ wait(&ret);
+ if (!WIFEXITED(ret))
+ ksft_print_msg("[INFO] wait() failed\n");
+ }
+ break;
+ case RO_PIN_TEST_RO_EXCLUSIVE:
+ /*
+ * Map the page R/O into the page table. Enable softdirty
+ * tracking to stop the page from getting mapped R/W immediately
+ * again by mprotect() optimizations. Note that we don't have an
+ * easy way to test if that worked (the pagemap does not export
+ * if the page is mapped R/O vs. R/W).
+ */
+ ret = mprotect(mem, size, PROT_READ);
+ clear_softdirty();
+ ret |= mprotect(mem, size, PROT_READ | PROT_WRITE);
+ if (ret) {
+ ksft_test_result_fail("mprotect() failed\n");
+ goto close_comm_pipes;
+ }
+ break;
+ default:
+ assert(false);
+ }
+
+ /* Take a R/O pin. This should trigger unsharing. */
+ args.addr = (__u64)(uintptr_t)mem;
+ args.size = size;
+ args.flags = fast ? PIN_LONGTERM_TEST_FLAG_USE_FAST : 0;
+ ret = ioctl(gup_fd, PIN_LONGTERM_TEST_START, &args);
+ if (ret) {
+ if (errno == EINVAL)
+ ksft_test_result_skip("PIN_LONGTERM_TEST_START failed\n");
+ else
+ ksft_test_result_fail("PIN_LONGTERM_TEST_START failed\n");
+ goto wait;
+ }
+
+ /* Modify the page. */
+ memset(mem, 0xff, size);
+
+ /*
+ * Read back the content via the pin to the temporary buffer and
+ * test if we observed the modification.
+ */
+ tmp_val = (__u64)(uintptr_t)tmp;
+ ret = ioctl(gup_fd, PIN_LONGTERM_TEST_READ, &tmp_val);
+ if (ret)
+ ksft_test_result_fail("PIN_LONGTERM_TEST_READ failed\n");
+ else
+ ksft_test_result(!memcmp(mem, tmp, size),
+ "Longterm R/O pin is reliable\n");
+
+ ret = ioctl(gup_fd, PIN_LONGTERM_TEST_STOP);
+ if (ret)
+ ksft_print_msg("[INFO] PIN_LONGTERM_TEST_STOP failed\n");
+wait:
+ switch (test) {
+ case RO_PIN_TEST_SHARED:
+ write(comm_pipes.parent_ready[1], "0", 1);
+ wait(&ret);
+ if (!WIFEXITED(ret))
+ ksft_print_msg("[INFO] wait() failed\n");
+ break;
+ default:
+ break;
+ }
+close_comm_pipes:
+ close_comm_pipes(&comm_pipes);
+free_tmp:
+ free(tmp);
+}
+
+static void test_ro_pin_on_shared(char *mem, size_t size)
+{
+ do_test_ro_pin(mem, size, RO_PIN_TEST_SHARED, false);
+}
+
+static void test_ro_fast_pin_on_shared(char *mem, size_t size)
+{
+ do_test_ro_pin(mem, size, RO_PIN_TEST_SHARED, true);
+}
+
+static void test_ro_pin_on_ro_previously_shared(char *mem, size_t size)
+{
+ do_test_ro_pin(mem, size, RO_PIN_TEST_PREVIOUSLY_SHARED, false);
+}
+
+static void test_ro_fast_pin_on_ro_previously_shared(char *mem, size_t size)
+{
+ do_test_ro_pin(mem, size, RO_PIN_TEST_PREVIOUSLY_SHARED, true);
+}
+
+static void test_ro_pin_on_ro_exclusive(char *mem, size_t size)
+{
+ do_test_ro_pin(mem, size, RO_PIN_TEST_RO_EXCLUSIVE, false);
+}
+
+static void test_ro_fast_pin_on_ro_exclusive(char *mem, size_t size)
+{
+ do_test_ro_pin(mem, size, RO_PIN_TEST_RO_EXCLUSIVE, true);
+}
+
+typedef void (*test_fn)(char *mem, size_t size);
+
+static void do_run_with_base_page(test_fn fn, bool swapout)
+{
+ char *mem;
+ int ret;
+
+ mem = mmap(NULL, pagesize, PROT_READ | PROT_WRITE,
+ MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);
+ if (mem == MAP_FAILED) {
+ ksft_test_result_fail("mmap() failed\n");
+ return;
+ }
+
+ ret = madvise(mem, pagesize, MADV_NOHUGEPAGE);
+ /* Ignore if not around on a kernel. */
+ if (ret && errno != EINVAL) {
+ ksft_test_result_fail("MADV_NOHUGEPAGE failed\n");
+ goto munmap;
+ }
+
+ /* Populate a base page. */
+ memset(mem, 0, pagesize);
+
+ if (swapout) {
+ madvise(mem, pagesize, MADV_PAGEOUT);
+ if (!pagemap_is_swapped(pagemap_fd, mem)) {
+ ksft_test_result_skip("MADV_PAGEOUT did not work, is swap enabled?\n");
+ goto munmap;
+ }
+ }
+
+ fn(mem, pagesize);
+munmap:
+ munmap(mem, pagesize);
+}
+
+static void run_with_base_page(test_fn fn, const char *desc)
+{
+ ksft_print_msg("[RUN] %s ... with base page\n", desc);
+ do_run_with_base_page(fn, false);
+}
+
+static void run_with_base_page_swap(test_fn fn, const char *desc)
+{
+ ksft_print_msg("[RUN] %s ... with swapped out base page\n", desc);
+ do_run_with_base_page(fn, true);
+}
+
+enum thp_run {
+ THP_RUN_PMD,
+ THP_RUN_PMD_SWAPOUT,
+ THP_RUN_PTE,
+ THP_RUN_PTE_SWAPOUT,
+ THP_RUN_SINGLE_PTE,
+ THP_RUN_SINGLE_PTE_SWAPOUT,
+ THP_RUN_PARTIAL_MREMAP,
+ THP_RUN_PARTIAL_SHARED,
+};
+
+static void do_run_with_thp(test_fn fn, enum thp_run thp_run)
+{
+ char *mem, *mmap_mem, *tmp, *mremap_mem = MAP_FAILED;
+ size_t size, mmap_size, mremap_size;
+ int ret;
+
+ /* For alignment purposes, we need twice the thp size. */
+ mmap_size = 2 * thpsize;
+ mmap_mem = mmap(NULL, mmap_size, PROT_READ | PROT_WRITE,
+ MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);
+ if (mmap_mem == MAP_FAILED) {
+ ksft_test_result_fail("mmap() failed\n");
+ return;
+ }
+
+ /* We need a THP-aligned memory area. */
+ mem = (char *)(((uintptr_t)mmap_mem + thpsize) & ~(thpsize - 1));
+
+ ret = madvise(mem, thpsize, MADV_HUGEPAGE);
+ if (ret) {
+ ksft_test_result_fail("MADV_HUGEPAGE failed\n");
+ goto munmap;
+ }
+
+ /*
+ * Try to populate a THP. Touch the first sub-page and test if we get
+ * another sub-page populated automatically.
+ */
+ mem[0] = 0;
+ if (!pagemap_is_populated(pagemap_fd, mem + pagesize)) {
+ ksft_test_result_skip("Did not get a THP populated\n");
+ goto munmap;
+ }
+ memset(mem, 0, thpsize);
+
+ size = thpsize;
+ switch (thp_run) {
+ case THP_RUN_PMD:
+ case THP_RUN_PMD_SWAPOUT:
+ break;
+ case THP_RUN_PTE:
+ case THP_RUN_PTE_SWAPOUT:
+ /*
+ * Trigger PTE-mapping the THP by temporarily mapping a single
+ * subpage R/O.
+ */
+ ret = mprotect(mem + pagesize, pagesize, PROT_READ);
+ if (ret) {
+ ksft_test_result_fail("mprotect() failed\n");
+ goto munmap;
+ }
+ ret = mprotect(mem + pagesize, pagesize, PROT_READ | PROT_WRITE);
+ if (ret) {
+ ksft_test_result_fail("mprotect() failed\n");
+ goto munmap;
+ }
+ break;
+ case THP_RUN_SINGLE_PTE:
+ case THP_RUN_SINGLE_PTE_SWAPOUT:
+ /*
+ * Discard all but a single subpage of that PTE-mapped THP. What
+ * remains is a single PTE mapping a single subpage.
+ */
+ ret = madvise(mem + pagesize, thpsize - pagesize, MADV_DONTNEED);
+ if (ret) {
+ ksft_test_result_fail("MADV_DONTNEED failed\n");
+ goto munmap;
+ }
+ size = pagesize;
+ break;
+ case THP_RUN_PARTIAL_MREMAP:
+ /*
+ * Remap half of the THP. We need some new memory location
+ * for that.
+ */
+ mremap_size = thpsize / 2;
+ mremap_mem = mmap(NULL, mremap_size, PROT_NONE,
+ MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);
+ if (mem == MAP_FAILED) {
+ ksft_test_result_fail("mmap() failed\n");
+ goto munmap;
+ }
+ tmp = mremap(mem + mremap_size, mremap_size, mremap_size,
+ MREMAP_MAYMOVE | MREMAP_FIXED, mremap_mem);
+ if (tmp != mremap_mem) {
+ ksft_test_result_fail("mremap() failed\n");
+ goto munmap;
+ }
+ size = mremap_size;
+ break;
+ case THP_RUN_PARTIAL_SHARED:
+ /*
+ * Share the first page of the THP with a child and quit the
+ * child. This will result in some parts of the THP never
+ * have been shared.
+ */
+ ret = madvise(mem + pagesize, thpsize - pagesize, MADV_DONTFORK);
+ if (ret) {
+ ksft_test_result_fail("MADV_DONTFORK failed\n");
+ goto munmap;
+ }
+ ret = fork();
+ if (ret < 0) {
+ ksft_test_result_fail("fork() failed\n");
+ goto munmap;
+ } else if (!ret) {
+ exit(0);
+ }
+ wait(&ret);
+ /* Allow for sharing all pages again. */
+ ret = madvise(mem + pagesize, thpsize - pagesize, MADV_DOFORK);
+ if (ret) {
+ ksft_test_result_fail("MADV_DOFORK failed\n");
+ goto munmap;
+ }
+ break;
+ default:
+ assert(false);
+ }
+
+ switch (thp_run) {
+ case THP_RUN_PMD_SWAPOUT:
+ case THP_RUN_PTE_SWAPOUT:
+ case THP_RUN_SINGLE_PTE_SWAPOUT:
+ madvise(mem, size, MADV_PAGEOUT);
+ if (!range_is_swapped(mem, size)) {
+ ksft_test_result_skip("MADV_PAGEOUT did not work, is swap enabled?\n");
+ goto munmap;
+ }
+ break;
+ default:
+ break;
+ }
+
+ fn(mem, size);
+munmap:
+ munmap(mmap_mem, mmap_size);
+ if (mremap_mem != MAP_FAILED)
+ munmap(mremap_mem, mremap_size);
+}
+
+static void run_with_thp(test_fn fn, const char *desc)
+{
+ ksft_print_msg("[RUN] %s ... with THP\n", desc);
+ do_run_with_thp(fn, THP_RUN_PMD);
+}
+
+static void run_with_thp_swap(test_fn fn, const char *desc)
+{
+ ksft_print_msg("[RUN] %s ... with swapped-out THP\n", desc);
+ do_run_with_thp(fn, THP_RUN_PMD_SWAPOUT);
+}
+
+static void run_with_pte_mapped_thp(test_fn fn, const char *desc)
+{
+ ksft_print_msg("[RUN] %s ... with PTE-mapped THP\n", desc);
+ do_run_with_thp(fn, THP_RUN_PTE);
+}
+
+static void run_with_pte_mapped_thp_swap(test_fn fn, const char *desc)
+{
+ ksft_print_msg("[RUN] %s ... with swapped-out, PTE-mapped THP\n", desc);
+ do_run_with_thp(fn, THP_RUN_PTE_SWAPOUT);
+}
+
+static void run_with_single_pte_of_thp(test_fn fn, const char *desc)
+{
+ ksft_print_msg("[RUN] %s ... with single PTE of THP\n", desc);
+ do_run_with_thp(fn, THP_RUN_SINGLE_PTE);
+}
+
+static void run_with_single_pte_of_thp_swap(test_fn fn, const char *desc)
+{
+ ksft_print_msg("[RUN] %s ... with single PTE of swapped-out THP\n", desc);
+ do_run_with_thp(fn, THP_RUN_SINGLE_PTE_SWAPOUT);
+}
+
+static void run_with_partial_mremap_thp(test_fn fn, const char *desc)
+{
+ ksft_print_msg("[RUN] %s ... with partially mremap()'ed THP\n", desc);
+ do_run_with_thp(fn, THP_RUN_PARTIAL_MREMAP);
+}
+
+static void run_with_partial_shared_thp(test_fn fn, const char *desc)
+{
+ ksft_print_msg("[RUN] %s ... with partially shared THP\n", desc);
+ do_run_with_thp(fn, THP_RUN_PARTIAL_SHARED);
+}
+
+static void run_with_hugetlb(test_fn fn, const char *desc, size_t hugetlbsize)
+{
+ int flags = MAP_PRIVATE | MAP_ANONYMOUS | MAP_HUGETLB;
+ char *mem, *dummy;
+
+ ksft_print_msg("[RUN] %s ... with hugetlb (%zu kB)\n", desc,
+ hugetlbsize / 1024);
+
+ flags |= __builtin_ctzll(hugetlbsize) << MAP_HUGE_SHIFT;
+
+ mem = mmap(NULL, hugetlbsize, PROT_READ | PROT_WRITE, flags, -1, 0);
+ if (mem == MAP_FAILED) {
+ ksft_test_result_skip("need more free huge pages\n");
+ return;
+ }
+
+ /* Populate an huge page. */
+ memset(mem, 0, hugetlbsize);
+
+ /*
+ * We need a total of two hugetlb pages to handle COW/unsharing
+ * properly, otherwise we might get zapped by a SIGBUS.
+ */
+ dummy = mmap(NULL, hugetlbsize, PROT_READ | PROT_WRITE, flags, -1, 0);
+ if (dummy == MAP_FAILED) {
+ ksft_test_result_skip("need more free huge pages\n");
+ goto munmap;
+ }
+ munmap(dummy, hugetlbsize);
+
+ fn(mem, hugetlbsize);
+munmap:
+ munmap(mem, hugetlbsize);
+}
+
+struct test_case {
+ const char *desc;
+ test_fn fn;
+};
+
+/*
+ * Test cases that are specific to anonymous pages: pages in private mappings
+ * that may get shared via COW during fork().
+ */
+static const struct test_case anon_test_cases[] = {
+ /*
+ * Basic COW tests for fork() without any GUP. If we miss to break COW,
+ * either the child can observe modifications by the parent or the
+ * other way around.
+ */
+ {
+ "Basic COW after fork()",
+ test_cow_in_parent,
+ },
+ /*
+ * Basic test, but do an additional mprotect(PROT_READ)+
+ * mprotect(PROT_READ|PROT_WRITE) in the parent before write access.
+ */
+ {
+ "Basic COW after fork() with mprotect() optimization",
+ test_cow_in_parent_mprotect,
+ },
+ /*
+ * vmsplice() [R/O GUP] + unmap in the child; modify in the parent. If
+ * we miss to break COW, the child observes modifications by the parent.
+ * This is CVE-2020-29374 reported by Jann Horn.
+ */
+ {
+ "vmsplice() + unmap in child",
+ test_vmsplice_in_child
+ },
+ /*
+ * vmsplice() test, but do an additional mprotect(PROT_READ)+
+ * mprotect(PROT_READ|PROT_WRITE) in the parent before write access.
+ */
+ {
+ "vmsplice() + unmap in child with mprotect() optimization",
+ test_vmsplice_in_child_mprotect
+ },
+ /*
+ * vmsplice() [R/O GUP] in parent before fork(), unmap in parent after
+ * fork(); modify in the child. If we miss to break COW, the parent
+ * observes modifications by the child.
+ */
+ {
+ "vmsplice() before fork(), unmap in parent after fork()",
+ test_vmsplice_before_fork,
+ },
+ /*
+ * vmsplice() [R/O GUP] + unmap in parent after fork(); modify in the
+ * child. If we miss to break COW, the parent observes modifications by
+ * the child.
+ */
+ {
+ "vmsplice() + unmap in parent after fork()",
+ test_vmsplice_after_fork,
+ },
+#ifdef LOCAL_CONFIG_HAVE_LIBURING
+ /*
+ * Take a R/W longterm pin and then map the page R/O into the page
+ * table to trigger a write fault on next access. When modifying the
+ * page, the page content must be visible via the pin.
+ */
+ {
+ "R/O-mapping a page registered as iouring fixed buffer",
+ test_iouring_ro,
+ },
+ /*
+ * Take a R/W longterm pin and then fork() a child. When modifying the
+ * page, the page content must be visible via the pin. We expect the
+ * pinned page to not get shared with the child.
+ */
+ {
+ "fork() with an iouring fixed buffer",
+ test_iouring_fork,
+ },
+
+#endif /* LOCAL_CONFIG_HAVE_LIBURING */
+ /*
+ * Take a R/O longterm pin on a R/O-mapped shared anonymous page.
+ * When modifying the page via the page table, the page content change
+ * must be visible via the pin.
+ */
+ {
+ "R/O GUP pin on R/O-mapped shared page",
+ test_ro_pin_on_shared,
+ },
+ /* Same as above, but using GUP-fast. */
+ {
+ "R/O GUP-fast pin on R/O-mapped shared page",
+ test_ro_fast_pin_on_shared,
+ },
+ /*
+ * Take a R/O longterm pin on a R/O-mapped exclusive anonymous page that
+ * was previously shared. When modifying the page via the page table,
+ * the page content change must be visible via the pin.
+ */
+ {
+ "R/O GUP pin on R/O-mapped previously-shared page",
+ test_ro_pin_on_ro_previously_shared,
+ },
+ /* Same as above, but using GUP-fast. */
+ {
+ "R/O GUP-fast pin on R/O-mapped previously-shared page",
+ test_ro_fast_pin_on_ro_previously_shared,
+ },
+ /*
+ * Take a R/O longterm pin on a R/O-mapped exclusive anonymous page.
+ * When modifying the page via the page table, the page content change
+ * must be visible via the pin.
+ */
+ {
+ "R/O GUP pin on R/O-mapped exclusive page",
+ test_ro_pin_on_ro_exclusive,
+ },
+ /* Same as above, but using GUP-fast. */
+ {
+ "R/O GUP-fast pin on R/O-mapped exclusive page",
+ test_ro_fast_pin_on_ro_exclusive,
+ },
+};
+
+static void run_anon_test_case(struct test_case const *test_case)
+{
+ int i;
+
+ run_with_base_page(test_case->fn, test_case->desc);
+ run_with_base_page_swap(test_case->fn, test_case->desc);
+ if (thpsize) {
+ run_with_thp(test_case->fn, test_case->desc);
+ run_with_thp_swap(test_case->fn, test_case->desc);
+ run_with_pte_mapped_thp(test_case->fn, test_case->desc);
+ run_with_pte_mapped_thp_swap(test_case->fn, test_case->desc);
+ run_with_single_pte_of_thp(test_case->fn, test_case->desc);
+ run_with_single_pte_of_thp_swap(test_case->fn, test_case->desc);
+ run_with_partial_mremap_thp(test_case->fn, test_case->desc);
+ run_with_partial_shared_thp(test_case->fn, test_case->desc);
+ }
+ for (i = 0; i < nr_hugetlbsizes; i++)
+ run_with_hugetlb(test_case->fn, test_case->desc,
+ hugetlbsizes[i]);
+}
+
+static void run_anon_test_cases(void)
+{
+ int i;
+
+ ksft_print_msg("[INFO] Anonymous memory tests in private mappings\n");
+
+ for (i = 0; i < ARRAY_SIZE(anon_test_cases); i++)
+ run_anon_test_case(&anon_test_cases[i]);
+}
+
+static int tests_per_anon_test_case(void)
+{
+ int tests = 2 + nr_hugetlbsizes;
+
+ if (thpsize)
+ tests += 8;
+ return tests;
+}
+
+enum anon_thp_collapse_test {
+ ANON_THP_COLLAPSE_UNSHARED,
+ ANON_THP_COLLAPSE_FULLY_SHARED,
+ ANON_THP_COLLAPSE_LOWER_SHARED,
+ ANON_THP_COLLAPSE_UPPER_SHARED,
+};
+
+static void do_test_anon_thp_collapse(char *mem, size_t size,
+ enum anon_thp_collapse_test test)
+{
+ struct comm_pipes comm_pipes;
+ char buf;
+ int ret;
+
+ ret = setup_comm_pipes(&comm_pipes);
+ if (ret) {
+ ksft_test_result_fail("pipe() failed\n");
+ return;
+ }
+
+ /*
+ * Trigger PTE-mapping the THP by temporarily mapping a single subpage
+ * R/O, such that we can try collapsing it later.
+ */
+ ret = mprotect(mem + pagesize, pagesize, PROT_READ);
+ if (ret) {
+ ksft_test_result_fail("mprotect() failed\n");
+ goto close_comm_pipes;
+ }
+ ret = mprotect(mem + pagesize, pagesize, PROT_READ | PROT_WRITE);
+ if (ret) {
+ ksft_test_result_fail("mprotect() failed\n");
+ goto close_comm_pipes;
+ }
+
+ switch (test) {
+ case ANON_THP_COLLAPSE_UNSHARED:
+ /* Collapse before actually COW-sharing the page. */
+ ret = madvise(mem, size, MADV_COLLAPSE);
+ if (ret) {
+ ksft_test_result_skip("MADV_COLLAPSE failed: %s\n",
+ strerror(errno));
+ goto close_comm_pipes;
+ }
+ break;
+ case ANON_THP_COLLAPSE_FULLY_SHARED:
+ /* COW-share the full PTE-mapped THP. */
+ break;
+ case ANON_THP_COLLAPSE_LOWER_SHARED:
+ /* Don't COW-share the upper part of the THP. */
+ ret = madvise(mem + size / 2, size / 2, MADV_DONTFORK);
+ if (ret) {
+ ksft_test_result_fail("MADV_DONTFORK failed\n");
+ goto close_comm_pipes;
+ }
+ break;
+ case ANON_THP_COLLAPSE_UPPER_SHARED:
+ /* Don't COW-share the lower part of the THP. */
+ ret = madvise(mem, size / 2, MADV_DONTFORK);
+ if (ret) {
+ ksft_test_result_fail("MADV_DONTFORK failed\n");
+ goto close_comm_pipes;
+ }
+ break;
+ default:
+ assert(false);
+ }
+
+ ret = fork();
+ if (ret < 0) {
+ ksft_test_result_fail("fork() failed\n");
+ goto close_comm_pipes;
+ } else if (!ret) {
+ switch (test) {
+ case ANON_THP_COLLAPSE_UNSHARED:
+ case ANON_THP_COLLAPSE_FULLY_SHARED:
+ exit(child_memcmp_fn(mem, size, &comm_pipes));
+ break;
+ case ANON_THP_COLLAPSE_LOWER_SHARED:
+ exit(child_memcmp_fn(mem, size / 2, &comm_pipes));
+ break;
+ case ANON_THP_COLLAPSE_UPPER_SHARED:
+ exit(child_memcmp_fn(mem + size / 2, size / 2,
+ &comm_pipes));
+ break;
+ default:
+ assert(false);
+ }
+ }
+
+ while (read(comm_pipes.child_ready[0], &buf, 1) != 1)
+ ;
+
+ switch (test) {
+ case ANON_THP_COLLAPSE_UNSHARED:
+ break;
+ case ANON_THP_COLLAPSE_UPPER_SHARED:
+ case ANON_THP_COLLAPSE_LOWER_SHARED:
+ /*
+ * Revert MADV_DONTFORK such that we merge the VMAs and are
+ * able to actually collapse.
+ */
+ ret = madvise(mem, size, MADV_DOFORK);
+ if (ret) {
+ ksft_test_result_fail("MADV_DOFORK failed\n");
+ write(comm_pipes.parent_ready[1], "0", 1);
+ wait(&ret);
+ goto close_comm_pipes;
+ }
+ /* FALLTHROUGH */
+ case ANON_THP_COLLAPSE_FULLY_SHARED:
+ /* Collapse before anyone modified the COW-shared page. */
+ ret = madvise(mem, size, MADV_COLLAPSE);
+ if (ret) {
+ ksft_test_result_skip("MADV_COLLAPSE failed: %s\n",
+ strerror(errno));
+ write(comm_pipes.parent_ready[1], "0", 1);
+ wait(&ret);
+ goto close_comm_pipes;
+ }
+ break;
+ default:
+ assert(false);
+ }
+
+ /* Modify the page. */
+ memset(mem, 0xff, size);
+ write(comm_pipes.parent_ready[1], "0", 1);
+
+ wait(&ret);
+ if (WIFEXITED(ret))
+ ret = WEXITSTATUS(ret);
+ else
+ ret = -EINVAL;
+
+ ksft_test_result(!ret, "No leak from parent into child\n");
+close_comm_pipes:
+ close_comm_pipes(&comm_pipes);
+}
+
+static void test_anon_thp_collapse_unshared(char *mem, size_t size)
+{
+ do_test_anon_thp_collapse(mem, size, ANON_THP_COLLAPSE_UNSHARED);
+}
+
+static void test_anon_thp_collapse_fully_shared(char *mem, size_t size)
+{
+ do_test_anon_thp_collapse(mem, size, ANON_THP_COLLAPSE_FULLY_SHARED);
+}
+
+static void test_anon_thp_collapse_lower_shared(char *mem, size_t size)
+{
+ do_test_anon_thp_collapse(mem, size, ANON_THP_COLLAPSE_LOWER_SHARED);
+}
+
+static void test_anon_thp_collapse_upper_shared(char *mem, size_t size)
+{
+ do_test_anon_thp_collapse(mem, size, ANON_THP_COLLAPSE_UPPER_SHARED);
+}
+
+/*
+ * Test cases that are specific to anonymous THP: pages in private mappings
+ * that may get shared via COW during fork().
+ */
+static const struct test_case anon_thp_test_cases[] = {
+ /*
+ * Basic COW test for fork() without any GUP when collapsing a THP
+ * before fork().
+ *
+ * Re-mapping a PTE-mapped anon THP using a single PMD ("in-place
+ * collapse") might easily get COW handling wrong when not collapsing
+ * exclusivity information properly.
+ */
+ {
+ "Basic COW after fork() when collapsing before fork()",
+ test_anon_thp_collapse_unshared,
+ },
+ /* Basic COW test, but collapse after COW-sharing a full THP. */
+ {
+ "Basic COW after fork() when collapsing after fork() (fully shared)",
+ test_anon_thp_collapse_fully_shared,
+ },
+ /*
+ * Basic COW test, but collapse after COW-sharing the lower half of a
+ * THP.
+ */
+ {
+ "Basic COW after fork() when collapsing after fork() (lower shared)",
+ test_anon_thp_collapse_lower_shared,
+ },
+ /*
+ * Basic COW test, but collapse after COW-sharing the upper half of a
+ * THP.
+ */
+ {
+ "Basic COW after fork() when collapsing after fork() (upper shared)",
+ test_anon_thp_collapse_upper_shared,
+ },
+};
+
+static void run_anon_thp_test_cases(void)
+{
+ int i;
+
+ if (!thpsize)
+ return;
+
+ ksft_print_msg("[INFO] Anonymous THP tests\n");
+
+ for (i = 0; i < ARRAY_SIZE(anon_thp_test_cases); i++) {
+ struct test_case const *test_case = &anon_thp_test_cases[i];
+
+ ksft_print_msg("[RUN] %s\n", test_case->desc);
+ do_run_with_thp(test_case->fn, THP_RUN_PMD);
+ }
+}
+
+static int tests_per_anon_thp_test_case(void)
+{
+ return thpsize ? 1 : 0;
+}
+
+typedef void (*non_anon_test_fn)(char *mem, const char *smem, size_t size);
+
+static void test_cow(char *mem, const char *smem, size_t size)
+{
+ char *old = malloc(size);
+
+ /* Backup the original content. */
+ memcpy(old, smem, size);
+
+ /* Modify the page. */
+ memset(mem, 0xff, size);
+
+ /* See if we still read the old values via the other mapping. */
+ ksft_test_result(!memcmp(smem, old, size),
+ "Other mapping not modified\n");
+ free(old);
+}
+
+static void test_ro_pin(char *mem, const char *smem, size_t size)
+{
+ do_test_ro_pin(mem, size, RO_PIN_TEST, false);
+}
+
+static void test_ro_fast_pin(char *mem, const char *smem, size_t size)
+{
+ do_test_ro_pin(mem, size, RO_PIN_TEST, true);
+}
+
+static void run_with_zeropage(non_anon_test_fn fn, const char *desc)
+{
+ char *mem, *smem, tmp;
+
+ ksft_print_msg("[RUN] %s ... with shared zeropage\n", desc);
+
+ mem = mmap(NULL, pagesize, PROT_READ | PROT_WRITE,
+ MAP_PRIVATE | MAP_ANON, -1, 0);
+ if (mem == MAP_FAILED) {
+ ksft_test_result_fail("mmap() failed\n");
+ return;
+ }
+
+ smem = mmap(NULL, pagesize, PROT_READ, MAP_PRIVATE | MAP_ANON, -1, 0);
+ if (mem == MAP_FAILED) {
+ ksft_test_result_fail("mmap() failed\n");
+ goto munmap;
+ }
+
+ /* Read from the page to populate the shared zeropage. */
+ tmp = *mem + *smem;
+ asm volatile("" : "+r" (tmp));
+
+ fn(mem, smem, pagesize);
+munmap:
+ munmap(mem, pagesize);
+ if (smem != MAP_FAILED)
+ munmap(smem, pagesize);
+}
+
+static void run_with_huge_zeropage(non_anon_test_fn fn, const char *desc)
+{
+ char *mem, *smem, *mmap_mem, *mmap_smem, tmp;
+ size_t mmap_size;
+ int ret;
+
+ ksft_print_msg("[RUN] %s ... with huge zeropage\n", desc);
+
+ if (!has_huge_zeropage) {
+ ksft_test_result_skip("Huge zeropage not enabled\n");
+ return;
+ }
+
+ /* For alignment purposes, we need twice the thp size. */
+ mmap_size = 2 * thpsize;
+ mmap_mem = mmap(NULL, mmap_size, PROT_READ | PROT_WRITE,
+ MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);
+ if (mmap_mem == MAP_FAILED) {
+ ksft_test_result_fail("mmap() failed\n");
+ return;
+ }
+ mmap_smem = mmap(NULL, mmap_size, PROT_READ,
+ MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);
+ if (mmap_smem == MAP_FAILED) {
+ ksft_test_result_fail("mmap() failed\n");
+ goto munmap;
+ }
+
+ /* We need a THP-aligned memory area. */
+ mem = (char *)(((uintptr_t)mmap_mem + thpsize) & ~(thpsize - 1));
+ smem = (char *)(((uintptr_t)mmap_smem + thpsize) & ~(thpsize - 1));
+
+ ret = madvise(mem, thpsize, MADV_HUGEPAGE);
+ ret |= madvise(smem, thpsize, MADV_HUGEPAGE);
+ if (ret) {
+ ksft_test_result_fail("MADV_HUGEPAGE failed\n");
+ goto munmap;
+ }
+
+ /*
+ * Read from the memory to populate the huge shared zeropage. Read from
+ * the first sub-page and test if we get another sub-page populated
+ * automatically.
+ */
+ tmp = *mem + *smem;
+ asm volatile("" : "+r" (tmp));
+ if (!pagemap_is_populated(pagemap_fd, mem + pagesize) ||
+ !pagemap_is_populated(pagemap_fd, smem + pagesize)) {
+ ksft_test_result_skip("Did not get THPs populated\n");
+ goto munmap;
+ }
+
+ fn(mem, smem, thpsize);
+munmap:
+ munmap(mmap_mem, mmap_size);
+ if (mmap_smem != MAP_FAILED)
+ munmap(mmap_smem, mmap_size);
+}
+
+static void run_with_memfd(non_anon_test_fn fn, const char *desc)
+{
+ char *mem, *smem, tmp;
+ int fd;
+
+ ksft_print_msg("[RUN] %s ... with memfd\n", desc);
+
+ fd = memfd_create("test", 0);
+ if (fd < 0) {
+ ksft_test_result_fail("memfd_create() failed\n");
+ return;
+ }
+
+ /* File consists of a single page filled with zeroes. */
+ if (fallocate(fd, 0, 0, pagesize)) {
+ ksft_test_result_fail("fallocate() failed\n");
+ goto close;
+ }
+
+ /* Create a private mapping of the memfd. */
+ mem = mmap(NULL, pagesize, PROT_READ | PROT_WRITE, MAP_PRIVATE, fd, 0);
+ if (mem == MAP_FAILED) {
+ ksft_test_result_fail("mmap() failed\n");
+ goto close;
+ }
+ smem = mmap(NULL, pagesize, PROT_READ, MAP_SHARED, fd, 0);
+ if (mem == MAP_FAILED) {
+ ksft_test_result_fail("mmap() failed\n");
+ goto munmap;
+ }
+
+ /* Fault the page in. */
+ tmp = *mem + *smem;
+ asm volatile("" : "+r" (tmp));
+
+ fn(mem, smem, pagesize);
+munmap:
+ munmap(mem, pagesize);
+ if (smem != MAP_FAILED)
+ munmap(smem, pagesize);
+close:
+ close(fd);
+}
+
+static void run_with_tmpfile(non_anon_test_fn fn, const char *desc)
+{
+ char *mem, *smem, tmp;
+ FILE *file;
+ int fd;
+
+ ksft_print_msg("[RUN] %s ... with tmpfile\n", desc);
+
+ file = tmpfile();
+ if (!file) {
+ ksft_test_result_fail("tmpfile() failed\n");
+ return;
+ }
+
+ fd = fileno(file);
+ if (fd < 0) {
+ ksft_test_result_skip("fileno() failed\n");
+ return;
+ }
+
+ /* File consists of a single page filled with zeroes. */
+ if (fallocate(fd, 0, 0, pagesize)) {
+ ksft_test_result_fail("fallocate() failed\n");
+ goto close;
+ }
+
+ /* Create a private mapping of the memfd. */
+ mem = mmap(NULL, pagesize, PROT_READ | PROT_WRITE, MAP_PRIVATE, fd, 0);
+ if (mem == MAP_FAILED) {
+ ksft_test_result_fail("mmap() failed\n");
+ goto close;
+ }
+ smem = mmap(NULL, pagesize, PROT_READ, MAP_SHARED, fd, 0);
+ if (mem == MAP_FAILED) {
+ ksft_test_result_fail("mmap() failed\n");
+ goto munmap;
+ }
+
+ /* Fault the page in. */
+ tmp = *mem + *smem;
+ asm volatile("" : "+r" (tmp));
+
+ fn(mem, smem, pagesize);
+munmap:
+ munmap(mem, pagesize);
+ if (smem != MAP_FAILED)
+ munmap(smem, pagesize);
+close:
+ fclose(file);
+}
+
+static void run_with_memfd_hugetlb(non_anon_test_fn fn, const char *desc,
+ size_t hugetlbsize)
+{
+ int flags = MFD_HUGETLB;
+ char *mem, *smem, tmp;
+ int fd;
+
+ ksft_print_msg("[RUN] %s ... with memfd hugetlb (%zu kB)\n", desc,
+ hugetlbsize / 1024);
+
+ flags |= __builtin_ctzll(hugetlbsize) << MFD_HUGE_SHIFT;
+
+ fd = memfd_create("test", flags);
+ if (fd < 0) {
+ ksft_test_result_skip("memfd_create() failed\n");
+ return;
+ }
+
+ /* File consists of a single page filled with zeroes. */
+ if (fallocate(fd, 0, 0, hugetlbsize)) {
+ ksft_test_result_skip("need more free huge pages\n");
+ goto close;
+ }
+
+ /* Create a private mapping of the memfd. */
+ mem = mmap(NULL, hugetlbsize, PROT_READ | PROT_WRITE, MAP_PRIVATE, fd,
+ 0);
+ if (mem == MAP_FAILED) {
+ ksft_test_result_skip("need more free huge pages\n");
+ goto close;
+ }
+ smem = mmap(NULL, hugetlbsize, PROT_READ, MAP_SHARED, fd, 0);
+ if (mem == MAP_FAILED) {
+ ksft_test_result_fail("mmap() failed\n");
+ goto munmap;
+ }
+
+ /* Fault the page in. */
+ tmp = *mem + *smem;
+ asm volatile("" : "+r" (tmp));
+
+ fn(mem, smem, hugetlbsize);
+munmap:
+ munmap(mem, hugetlbsize);
+ if (mem != MAP_FAILED)
+ munmap(smem, hugetlbsize);
+close:
+ close(fd);
+}
+
+struct non_anon_test_case {
+ const char *desc;
+ non_anon_test_fn fn;
+};
+
+/*
+ * Test cases that target any pages in private mappings that are not anonymous:
+ * pages that may get shared via COW ndependent of fork(). This includes
+ * the shared zeropage(s), pagecache pages, ...
+ */
+static const struct non_anon_test_case non_anon_test_cases[] = {
+ /*
+ * Basic COW test without any GUP. If we miss to break COW, changes are
+ * visible via other private/shared mappings.
+ */
+ {
+ "Basic COW",
+ test_cow,
+ },
+ /*
+ * Take a R/O longterm pin. When modifying the page via the page table,
+ * the page content change must be visible via the pin.
+ */
+ {
+ "R/O longterm GUP pin",
+ test_ro_pin,
+ },
+ /* Same as above, but using GUP-fast. */
+ {
+ "R/O longterm GUP-fast pin",
+ test_ro_fast_pin,
+ },
+};
+
+static void run_non_anon_test_case(struct non_anon_test_case const *test_case)
+{
+ int i;
+
+ run_with_zeropage(test_case->fn, test_case->desc);
+ run_with_memfd(test_case->fn, test_case->desc);
+ run_with_tmpfile(test_case->fn, test_case->desc);
+ if (thpsize)
+ run_with_huge_zeropage(test_case->fn, test_case->desc);
+ for (i = 0; i < nr_hugetlbsizes; i++)
+ run_with_memfd_hugetlb(test_case->fn, test_case->desc,
+ hugetlbsizes[i]);
+}
+
+static void run_non_anon_test_cases(void)
+{
+ int i;
+
+ ksft_print_msg("[RUN] Non-anonymous memory tests in private mappings\n");
+
+ for (i = 0; i < ARRAY_SIZE(non_anon_test_cases); i++)
+ run_non_anon_test_case(&non_anon_test_cases[i]);
+}
+
+static int tests_per_non_anon_test_case(void)
+{
+ int tests = 3 + nr_hugetlbsizes;
+
+ if (thpsize)
+ tests += 1;
+ return tests;
+}
+
+int main(int argc, char **argv)
+{
+ int err;
+
+ ksft_print_header();
+
+ pagesize = getpagesize();
+ thpsize = read_pmd_pagesize();
+ if (thpsize)
+ ksft_print_msg("[INFO] detected THP size: %zu KiB\n",
+ thpsize / 1024);
+ nr_hugetlbsizes = detect_hugetlb_page_sizes(hugetlbsizes,
+ ARRAY_SIZE(hugetlbsizes));
+ detect_huge_zeropage();
+
+ ksft_set_plan(ARRAY_SIZE(anon_test_cases) * tests_per_anon_test_case() +
+ ARRAY_SIZE(anon_thp_test_cases) * tests_per_anon_thp_test_case() +
+ ARRAY_SIZE(non_anon_test_cases) * tests_per_non_anon_test_case());
+
+ gup_fd = open("/sys/kernel/debug/gup_test", O_RDWR);
+ pagemap_fd = open("/proc/self/pagemap", O_RDONLY);
+ if (pagemap_fd < 0)
+ ksft_exit_fail_msg("opening pagemap failed\n");
+
+ run_anon_test_cases();
+ run_anon_thp_test_cases();
+ run_non_anon_test_cases();
+
+ err = ksft_get_fail_cnt();
+ if (err)
+ ksft_exit_fail_msg("%d out of %d tests failed\n",
+ err, ksft_test_num());
+ return ksft_exit_pass();
+}