userfaultfd: Add test using UFFDIO_MOVE

Signed-off-by: Ricardo Branco <rbranco@suse.de>
Reviewed-by: Petr Vorel <pvorel@suse.cz>
Reviewed-by: Cyril Hrubis <chrubis@suse.cz>
Link: #1280

Author: ricardobranco777

configure.ac

@@ -277,6 +277,8 @@ AC_CHECK_TYPES([struct sockaddr_vm],,,[
 #include <linux/vm_sockets.h>
 ])
 
+AC_CHECK_TYPES([struct uffdio_move],,,[#include <linux/userfaultfd.h>])
+
 # Tools knobs
 
 # Bash

include/lapi/userfaultfd.h

@@ -189,6 +189,30 @@ struct uffdio_continue {
 #define UFFD_FEATURE_MINOR_SHMEM		(1<<10)
 #endif /* UFFD_FEATURE_MINOR_SHMEM */
 
+#ifndef HAVE_STRUCT_UFFDIO_MOVE
+#define _UFFDIO_MOVE			(0x05)
+#define UFFDIO_MOVE		_IOWR(UFFDIO, _UFFDIO_MOVE,     \
+				      struct uffdio_move)
+
+struct uffdio_move {
+	__u64 dst;
+	__u64 src;
+	__u64 len;
+	/*
+	 * Especially if used to atomically remove memory from the
+	 * address space the wake on the dst range is not needed.
+	 */
+#define UFFDIO_MOVE_MODE_DONTWAKE		((__u64)1<<0)
+#define UFFDIO_MOVE_MODE_ALLOW_SRC_HOLES	((__u64)1<<1)
+	__u64 mode;
+	/*
+	 * "move" is written by the ioctl and must be at the end: the
+	 * copy_from_user will not read the last 8 bytes.
+	 */
+	__s64 move;
+};
+#endif	/* HAVE_STRUCT_UFFDIO_MOVE */
+
 #define SAFE_USERFAULTFD(flags, retry) \
 	safe_userfaultfd(__FILE__, __LINE__, (flags), (retry))
 

runtest/syscalls

@@ -1770,6 +1770,7 @@ umount2_01 umount2_01
 umount2_02 umount2_02
 
 userfaultfd01 userfaultfd01
+userfaultfd02 userfaultfd02
 
 ustat01 ustat01
 ustat02 ustat02

testcases/kernel/syscalls/userfaultfd/.gitignore

@@ -1 +1,2 @@
 /userfaultfd01
+/userfaultfd02

testcases/kernel/syscalls/userfaultfd/Makefile

@@ -12,3 +12,4 @@ include $(top_srcdir)/include/mk/testcases.mk
 include $(top_srcdir)/include/mk/generic_leaf_target.mk
 
 userfaultfd01: CFLAGS += -pthread
+userfaultfd02: CFLAGS += -pthread

testcases/kernel/syscalls/userfaultfd/userfaultfd02.c

@@ -0,0 +1,97 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * Copyright (c) 2025 SUSE LLC
+ * Author: Christian Amann <camann@suse.com>
+ * Author: Ricardo Branco <rbranco@suse.com>
+ */
+
+/*\
+ * Force a pagefault event and handle it using :manpage:`userfaultfd(2)`
+ * from a different thread using UFFDIO_MOVE.
+ */
+
+#include "config.h"
+#include "tst_test.h"
+#include "tst_safe_macros.h"
+#include "tst_safe_pthread.h"
+#include "lapi/userfaultfd.h"
+
+static int page_size;
+static char *page;
+static void *move_page;
+static int uffd;
+
+static void set_pages(void)
+{
+	page_size = sysconf(_SC_PAGE_SIZE);
+	page = SAFE_MMAP(NULL, page_size, PROT_READ | PROT_WRITE,
+			MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);
+	move_page = SAFE_MMAP(NULL, page_size, PROT_READ | PROT_WRITE,
+			MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);
+}
+
+static void reset_pages(void)
+{
+	SAFE_MUNMAP(page, page_size);
+	SAFE_MUNMAP(move_page, page_size);
+}
+
+static void *handle_thread(void)
+{
+	static struct uffd_msg msg;
+	struct uffdio_move uffdio_move = {};
+
+	SAFE_READ(1, uffd, &msg, sizeof(msg));
+
+	if (msg.event != UFFD_EVENT_PAGEFAULT)
+		tst_brk(TBROK | TERRNO, "Received unexpected UFFD_EVENT %d", msg.event);
+
+	memset(move_page, 'X', page_size);
+
+	uffdio_move.src = (unsigned long) move_page;
+
+	uffdio_move.dst = (unsigned long) msg.arg.pagefault.address
+			& ~(page_size - 1);
+	uffdio_move.len = page_size;
+	SAFE_IOCTL(uffd, UFFDIO_MOVE, &uffdio_move);
+
+	close(uffd);
+	return NULL;
+}
+
+static void run(void)
+{
+	pthread_t thr;
+	struct uffdio_api uffdio_api = {};
+	struct uffdio_register uffdio_register;
+
+	set_pages();
+
+	uffd = SAFE_USERFAULTFD(O_CLOEXEC, false);
+
+	uffdio_api.api = UFFD_API;
+	SAFE_IOCTL(uffd, UFFDIO_API, &uffdio_api);
+
+	uffdio_register.range.start = (unsigned long) page;
+	uffdio_register.range.len = page_size;
+	uffdio_register.mode = UFFDIO_REGISTER_MODE_MISSING;
+
+	SAFE_IOCTL(uffd, UFFDIO_REGISTER, &uffdio_register);
+
+	SAFE_PTHREAD_CREATE(&thr, NULL, (void *) handle_thread, NULL);
+
+	char c = page[0xf];
+
+	if (c == 'X')
+		tst_res(TPASS, "Pagefault handled via UFFDIO_MOVE");
+	else
+		tst_res(TFAIL, "Pagefault not handled via UFFDIO_MOVE");
+
+	SAFE_PTHREAD_JOIN(thr, NULL);
+	reset_pages();
+}
+
+static struct tst_test test = {
+	.test_all = run,
+	.min_kver = "6.8",
+};