selftests/mm: let uffd_handle_page_fault() take wp parameter

Make the handler optionally apply WP bit when resolving page faults for
either missing or minor page faults.  This moves towards removing global
test_uffdio_wp outside of the common code.

Link: https://lkml.kernel.org/r/20230412164341.328618-1-peterx@redhat.comSigned-off-by: Peter Xu <peterx@redhat.com>
Cc: Axel Rasmussen <axelrasmussen@google.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: Dmitry Safonov <0x7f454c46@gmail.com>
Cc: Mike Kravetz <mike.kravetz@oracle.com>
Cc: Mike Rapoport (IBM) <rppt@kernel.org>
Cc: Zach O'Keefe <zokeefe@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

tools/testing/selftests/mm/uffd-common.c

@@ -353,7 +353,7 @@ void wp_range(int ufd, __u64 start, __u64 len, bool wp)
 		err("clear WP failed: address=0x%"PRIx64, (uint64_t)start);
 }
 
-static void continue_range(int ufd, __u64 start, __u64 len)
+static void continue_range(int ufd, __u64 start, __u64 len, bool wp)
 {
 	struct uffdio_continue req;
 	int ret;
@@ -361,7 +361,7 @@ static void continue_range(int ufd, __u64 start, __u64 len)
 	req.range.start = start;
 	req.range.len = len;
 	req.mode = 0;
-	if (test_uffdio_wp)
+	if (wp)
 		req.mode |= UFFDIO_CONTINUE_MODE_WP;
 
 	if (ioctl(ufd, UFFDIO_CONTINUE, &req))
@@ -429,7 +429,8 @@ void uffd_handle_page_fault(struct uffd_msg *msg, struct uffd_args *args)
 				    area_dst_alias));
 		for (b = 0; b < page_size; ++b)
 			area[b] = ~area[b];
-		continue_range(uffd, msg->arg.pagefault.address, page_size);
+		continue_range(uffd, msg->arg.pagefault.address, page_size,
+			       args->apply_wp);
 		args->minor_faults++;
 	} else {
 		/*
@@ -459,7 +460,7 @@ void uffd_handle_page_fault(struct uffd_msg *msg, struct uffd_args *args)
 		offset = (char *)(unsigned long)msg->arg.pagefault.address - area_dst;
 		offset &= ~(page_size-1);
 
-		if (copy_page(uffd, offset))
+		if (copy_page(uffd, offset, args->apply_wp))
 			args->missing_faults++;
 	}
 }
@@ -555,7 +556,7 @@ static void wake_range(int ufd, unsigned long addr, unsigned long len)
 			addr), exit(1);
 }
 
-int __copy_page(int ufd, unsigned long offset, bool retry)
+int __copy_page(int ufd, unsigned long offset, bool retry, bool wp)
 {
 	struct uffdio_copy uffdio_copy;
 
@@ -564,7 +565,7 @@ int __copy_page(int ufd, unsigned long offset, bool retry)
 	uffdio_copy.dst = (unsigned long) area_dst + offset;
 	uffdio_copy.src = (unsigned long) area_src + offset;
 	uffdio_copy.len = page_size;
-	if (test_uffdio_wp)
+	if (wp)
 		uffdio_copy.mode = UFFDIO_COPY_MODE_WP;
 	else
 		uffdio_copy.mode = 0;
@@ -587,7 +588,7 @@ int __copy_page(int ufd, unsigned long offset, bool retry)
 	return 0;
 }
 
-int copy_page(int ufd, unsigned long offset)
+int copy_page(int ufd, unsigned long offset, bool wp)
 {
-	return __copy_page(ufd, offset, false);
+	return __copy_page(ufd, offset, false, wp);
 }

tools/testing/selftests/mm/uffd-common.h

@@ -72,6 +72,8 @@
 /* Userfaultfd test statistics */
 struct uffd_args {
 	int cpu;
+	/* Whether apply wr-protects when installing pages */
+	bool apply_wp;
 	unsigned long missing_faults;
 	unsigned long wp_faults;
 	unsigned long minor_faults;
@@ -104,8 +106,8 @@ void userfaultfd_open(uint64_t *features);
 int uffd_read_msg(int ufd, struct uffd_msg *msg);
 void wp_range(int ufd, __u64 start, __u64 len, bool wp);
 void uffd_handle_page_fault(struct uffd_msg *msg, struct uffd_args *args);
-int __copy_page(int ufd, unsigned long offset, bool retry);
-int copy_page(int ufd, unsigned long offset);
+int __copy_page(int ufd, unsigned long offset, bool retry, bool wp);
+int copy_page(int ufd, unsigned long offset, bool wp);
 void *uffd_poll_thread(void *arg);
 
 #define TEST_ANON	1

tools/testing/selftests/mm/uffd-stress.c

@@ -96,6 +96,7 @@ static void uffd_stats_reset(struct uffd_args *args, unsigned long n_cpus)
 
 	for (i = 0; i < n_cpus; i++) {
 		args[i].cpu = i;
+		args[i].apply_wp = test_uffdio_wp;
 		args[i].missing_faults = 0;
 		args[i].wp_faults = 0;
 		args[i].minor_faults = 0;
@@ -155,7 +156,7 @@ static void *locking_thread(void *arg)
 
 static int copy_page_retry(int ufd, unsigned long offset)
 {
-	return __copy_page(ufd, offset, true);
+	return __copy_page(ufd, offset, true, test_uffdio_wp);
 }
 
 pthread_mutex_t uffd_read_mutex = PTHREAD_MUTEX_INITIALIZER;
@@ -308,7 +309,7 @@ static void sighndl(int sig, siginfo_t *siginfo, void *ptr)
  * This also tests UFFD_FEATURE_EVENT_FORK event along with the signal
  * feature. Using monitor thread, verify no userfault events are generated.
  */
-static int faulting_process(int signal_test)
+static int faulting_process(int signal_test, bool wp)
 {
 	unsigned long nr;
 	unsigned long long count;
@@ -343,7 +344,7 @@ static int faulting_process(int signal_test)
 					if (steps == 1) {
 						/* This is a MISSING request */
 						steps++;
-						if (copy_page(uffd, offset))
+						if (copy_page(uffd, offset, wp))
 							signalled++;
 					} else {
 						/* This is a WP request */
@@ -507,6 +508,7 @@ static int userfaultfd_events_test(void)
 			  true, test_uffdio_wp, false))
 		err("register failure");
 
+	args.apply_wp = test_uffdio_wp;
 	if (pthread_create(&uffd_mon, &attr, uffd_poll_thread, &args))
 		err("uffd_poll_thread create");
 
@@ -515,7 +517,7 @@ static int userfaultfd_events_test(void)
 		err("fork");
 
 	if (!pid)
-		exit(faulting_process(0));
+		exit(faulting_process(0, test_uffdio_wp));
 
 	waitpid(pid, &err, 0);
 	if (err)
@@ -551,11 +553,12 @@ static int userfaultfd_sig_test(void)
 			  true, test_uffdio_wp, false))
 		err("register failure");
 
-	if (faulting_process(1))
+	if (faulting_process(1, test_uffdio_wp))
 		err("faulting process failed");
 
 	uffd_test_ops->release_pages(area_dst);
 
+	args.apply_wp = test_uffdio_wp;
 	if (pthread_create(&uffd_mon, &attr, uffd_poll_thread, &args))
 		err("uffd_poll_thread create");
 
@@ -564,7 +567,7 @@ static int userfaultfd_sig_test(void)
 		err("fork");
 
 	if (!pid)
-		exit(faulting_process(2));
+		exit(faulting_process(2, test_uffdio_wp));
 
 	waitpid(pid, &err, 0);
 	if (err)
@@ -628,6 +631,7 @@ static int userfaultfd_minor_test(void)
 		       page_size);
 	}
 
+	args.apply_wp = test_uffdio_wp;
 	if (pthread_create(&uffd_mon, &attr, uffd_poll_thread, &args))
 		err("uffd_poll_thread create");