selftests/mm: add tests for RO pinning vs fork() (760aee0b) · Commits · EulixOS / Software / Kernel

tools/testing/selftests/mm/uffd-unit-tests.c

+141 −3

Original line number	Original line	Diff line number	Diff line
	@@ -7,6 +7,8 @@

	#include "uffd-common.h"		#include "uffd-common.h"

			#include "../../../../mm/gup_test.h"

	#ifdef __NR_userfaultfd		#ifdef __NR_userfaultfd

	/* The unit test doesn't need a large or random size, make it 32MB for now */		/* The unit test doesn't need a large or random size, make it 32MB for now */
	@@ -247,7 +249,53 @@ static void fork_event_consumer(void data)
	return NULL;		return NULL;
	}		}

	static int pagemap_test_fork(int uffd, bool with_event)		typedef struct {
			int gup_fd;
			bool pinned;
			} pin_args;

			/*
			* Returns 0 if succeed, <0 for errors. pin_pages() needs to be paired
			* with unpin_pages(). Currently it needs to be RO longterm pin to satisfy
			* all needs of the test cases (e.g., trigger unshare, trigger fork() early
			* CoW, etc.).
			*/
			static int pin_pages(pin_args args, void buffer, size_t size)
			{
			struct pin_longterm_test test = {
			.addr = (uintptr_t)buffer,
			.size = size,
			/* Read-only pins */
			.flags = 0,
			};

			if (args->pinned)
			err("already pinned");

			args->gup_fd = open("/sys/kernel/debug/gup_test", O_RDWR);
			if (args->gup_fd < 0)
			return -errno;

			if (ioctl(args->gup_fd, PIN_LONGTERM_TEST_START, &test)) {
			/* Even if gup_test existed, can be an old gup_test / kernel */
			close(args->gup_fd);
			return -errno;
			}
			args->pinned = true;
			return 0;
			}

			static void unpin_pages(pin_args *args)
			{
			if (!args->pinned)
			err("unpin without pin first");
			if (ioctl(args->gup_fd, PIN_LONGTERM_TEST_STOP))
			err("PIN_LONGTERM_TEST_STOP");
			close(args->gup_fd);
			args->pinned = false;
			}

			static int pagemap_test_fork(int uffd, bool with_event, bool test_pin)
	{		{
	fork_event_args args = { .parent_uffd = uffd, .child_uffd = -1 };		fork_event_args args = { .parent_uffd = uffd, .child_uffd = -1 };
	pthread_t thread;		pthread_t thread;
	@@ -264,7 +312,17 @@ static int pagemap_test_fork(int uffd, bool with_event)
	child = fork();		child = fork();
	if (!child) {		if (!child) {
	/* Open the pagemap fd of the child itself */		/* Open the pagemap fd of the child itself */
			pin_args args = {};

	fd = pagemap_open();		fd = pagemap_open();

			if (test_pin && pin_pages(&args, area_dst, page_size))
			/*
			* Normally when reach here we have pinned in
			* previous tests, so shouldn't fail anymore
			*/
			err("pin page failed in child");

	value = pagemap_get_entry(fd, area_dst);		value = pagemap_get_entry(fd, area_dst);
	/*		/*
	* After fork(), we should handle uffd-wp bit differently:		* After fork(), we should handle uffd-wp bit differently:
	@@ -273,6 +331,8 @@ static int pagemap_test_fork(int uffd, bool with_event)
	* (2) when without EVENT_FORK, it should be dropped		* (2) when without EVENT_FORK, it should be dropped
	*/		*/
	pagemap_check_wp(value, with_event);		pagemap_check_wp(value, with_event);
			if (test_pin)
			unpin_pages(&args);
	/* Succeed */		/* Succeed */
	exit(0);		exit(0);
	}		}
	@@ -352,7 +412,7 @@ static void uffd_wp_fork_test_common(uffd_test_args_t *args,
	wp_range(uffd, (uint64_t)area_dst, page_size, true);		wp_range(uffd, (uint64_t)area_dst, page_size, true);
	value = pagemap_get_entry(pagemap_fd, area_dst);		value = pagemap_get_entry(pagemap_fd, area_dst);
	pagemap_check_wp(value, true);		pagemap_check_wp(value, true);
	if (pagemap_test_fork(uffd, with_event)) {		if (pagemap_test_fork(uffd, with_event, false)) {
	uffd_test_fail("Detected %s uffd-wp bit in child in present pte",		uffd_test_fail("Detected %s uffd-wp bit in child in present pte",
	with_event ? "missing" : "stall");		with_event ? "missing" : "stall");
	goto out;		goto out;
	@@ -383,7 +443,7 @@ static void uffd_wp_fork_test_common(uffd_test_args_t *args,
	/* Uffd-wp should persist even swapped out */		/* Uffd-wp should persist even swapped out */
	value = pagemap_get_entry(pagemap_fd, area_dst);		value = pagemap_get_entry(pagemap_fd, area_dst);
	pagemap_check_wp(value, true);		pagemap_check_wp(value, true);
	if (pagemap_test_fork(uffd, with_event)) {		if (pagemap_test_fork(uffd, with_event, false)) {
	uffd_test_fail("Detected %s uffd-wp bit in child in zapped pte",		uffd_test_fail("Detected %s uffd-wp bit in child in zapped pte",
	with_event ? "missing" : "stall");		with_event ? "missing" : "stall");
	goto out;		goto out;
	@@ -415,6 +475,68 @@ static void uffd_wp_fork_with_event_test(uffd_test_args_t *args)
	uffd_wp_fork_test_common(args, true);		uffd_wp_fork_test_common(args, true);
	}		}

			static void uffd_wp_fork_pin_test_common(uffd_test_args_t *args,
			bool with_event)
			{
			int pagemap_fd;
			pin_args pin_args = {};

			if (uffd_register(uffd, area_dst, page_size, false, true, false))
			err("register failed");

			pagemap_fd = pagemap_open();

			/* Touch the page */
			*area_dst = 1;
			wp_range(uffd, (uint64_t)area_dst, page_size, true);

			/*
			* 1. First pin, then fork(). This tests fork() special path when
			* doing early CoW if the page is private.
			*/
			if (pin_pages(&pin_args, area_dst, page_size)) {
			uffd_test_skip("Possibly CONFIG_GUP_TEST missing "
			"or unprivileged");
			close(pagemap_fd);
			uffd_unregister(uffd, area_dst, page_size);
			return;
			}

			if (pagemap_test_fork(uffd, with_event, false)) {
			uffd_test_fail("Detected %s uffd-wp bit in early CoW of fork()",
			with_event ? "missing" : "stall");
			unpin_pages(&pin_args);
			goto out;
			}

			unpin_pages(&pin_args);

			/*
			* 2. First fork(), then pin (in the child, where test_pin==true).
			* This tests COR, aka, page unsharing on private memories.
			*/
			if (pagemap_test_fork(uffd, with_event, true)) {
			uffd_test_fail("Detected %s uffd-wp bit when RO pin",
			with_event ? "missing" : "stall");
			goto out;
			}
			uffd_test_pass();
			out:
			if (uffd_unregister(uffd, area_dst, page_size))
			err("register failed");
			close(pagemap_fd);
			}

			static void uffd_wp_fork_pin_test(uffd_test_args_t *args)
			{
			uffd_wp_fork_pin_test_common(args, false);
			}

			static void uffd_wp_fork_pin_with_event_test(uffd_test_args_t *args)
			{
			uffd_wp_fork_pin_test_common(args, true);
			}

	static void check_memory_contents(char *p)		static void check_memory_contents(char *p)
	{		{
	unsigned long i, j;		unsigned long i, j;
	@@ -923,6 +1045,22 @@ uffd_test_case_t uffd_tests[] = {
	/* when set, child process should inherit uffd-wp bits */		/* when set, child process should inherit uffd-wp bits */
	UFFD_FEATURE_EVENT_FORK,		UFFD_FEATURE_EVENT_FORK,
	},		},
			{
			.name = "wp-fork-pin",
			.uffd_fn = uffd_wp_fork_pin_test,
			.mem_targets = MEM_ALL,
			.uffd_feature_required = UFFD_FEATURE_PAGEFAULT_FLAG_WP \|
			UFFD_FEATURE_WP_HUGETLBFS_SHMEM,
			},
			{
			.name = "wp-fork-pin-with-event",
			.uffd_fn = uffd_wp_fork_pin_with_event_test,
			.mem_targets = MEM_ALL,
			.uffd_feature_required = UFFD_FEATURE_PAGEFAULT_FLAG_WP \|
			UFFD_FEATURE_WP_HUGETLBFS_SHMEM \|
			/* when set, child process should inherit uffd-wp bits */
			UFFD_FEATURE_EVENT_FORK,
			},
	{		{
	.name = "wp-unpopulated",		.name = "wp-unpopulated",
	.uffd_fn = uffd_wp_unpopulated_test,		.uffd_fn = uffd_wp_unpopulated_test,