[PATCH v6 6/6] selftests/mm: add a GUP selftest

[Sarthak Sharma]

Add a new GUP selftest which uses kselftest_harness.h. Cover
12 mapping configurations: THP enabled, THP disabled and
HugeTLB, each across private/shared mappings and with/without
FOLL_WRITE. Run 7 testcases for every variant: get_user_pages,
get_user_pages_fast, pin_user_pages, pin_user_pages_fast,
pin_user_pages_longterm, and DUMP_USER_PAGES_TEST using both
get and pin.

Sweep four nr_pages_per_call values for each test: 1, 512, 123 and
all pages. This preserves the coverage previously provided by
run_gup_matrix(): 12 mapping combinations x 5 GUP/PUP operations x 4
batch sizes, for 240 ioctl calls. The two dump modes add another 96
calls.

Preserve the previous sparse dump coverage with a standalone test for
pages 0, 19 and 0x1000. In total the selftest reports 85 TAP
cases and issues 337 ioctls.

Add the new gup binary to the selftests/mm build, .gitignore,
run_vmtests.sh and MAINTAINERS. Update
Documentation/core-api/pin_user_pages.rst for the new test.

Suggested-by: David Hildenbrand (Arm) <david@xxxxxxxxxx>
Signed-off-by: Sarthak Sharma <sarthak.sharma@xxxxxxx>
---
 Documentation/core-api/pin_user_pages.rst |  14 +-
 MAINTAINERS                               |   1 +
 tools/testing/selftests/mm/.gitignore     |   1 +
 tools/testing/selftests/mm/Makefile       |   1 +
 tools/testing/selftests/mm/gup.c          | 341 ++++++++++++++++++++++
 tools/testing/selftests/mm/run_vmtests.sh |   1 +
 6 files changed, 355 insertions(+), 4 deletions(-)
 create mode 100644 tools/testing/selftests/mm/gup.c

diff --git a/Documentation/core-api/pin_user_pages.rst b/Documentation/core-api/pin_user_pages.rst
index c16ca163b55e..1564b16994ad 100644
--- a/Documentation/core-api/pin_user_pages.rst
+++ b/Documentation/core-api/pin_user_pages.rst
@@ -228,12 +228,18 @@ Unit testing
 ============
 This file::
 
- tools/testing/selftests/mm/gup_test.c
+ tools/testing/selftests/mm/gup.c
 
-has the following new calls to exercise the new pin*() wrapper functions:
+contains the following test cases to exercise pin_user_pages*():
 
-* PIN_FAST_BENCHMARK (./gup_test -a)
-* PIN_BASIC_TEST (./gup_test -b)
+* pin_user_pages via PIN_BASIC_TEST
+* pin_user_pages_fast via PIN_FAST_BENCHMARK
+* pin_user_pages_longterm via PIN_LONGTERM_BENCHMARK
+
+Run with::
+
+  make -C tools/testing/selftests/mm
+  ./tools/testing/selftests/mm/gup
 
 You can monitor how many total dma-pinned pages have been acquired and released
 since the system was booted, via two new /proc/vmstat entries: ::
diff --git a/MAINTAINERS b/MAINTAINERS
index 5845fa74a5a0..e59158c59a6e 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -17028,6 +17028,7 @@ F:	mm/gup.c
 F:	mm/gup_test.c
 F:	mm/gup_test.h
 F:	tools/mm/gup_bench.c
+F:	tools/testing/selftests/mm/gup.c
 F:	tools/testing/selftests/mm/gup_longterm.c
 
 MEMORY MANAGEMENT - KSM (Kernel Samepage Merging)
diff --git a/tools/testing/selftests/mm/.gitignore b/tools/testing/selftests/mm/.gitignore
index c30cd7ce635e..bf3a409dc219 100644
--- a/tools/testing/selftests/mm/.gitignore
+++ b/tools/testing/selftests/mm/.gitignore
@@ -50,6 +50,7 @@ local_config.h
 local_config.mk
 ksm_functional_tests
 mdwe_test
+gup
 gup_longterm
 mkdirty
 va_high_addr_switch
diff --git a/tools/testing/selftests/mm/Makefile b/tools/testing/selftests/mm/Makefile
index 44b16cbaee5b..0a15da7d3439 100644
--- a/tools/testing/selftests/mm/Makefile
+++ b/tools/testing/selftests/mm/Makefile
@@ -58,6 +58,7 @@ endif
 
 TEST_GEN_FILES = cow
 TEST_GEN_FILES += compaction_test
+TEST_GEN_FILES += gup
 TEST_GEN_FILES += gup_longterm
 TEST_GEN_FILES += hmm-tests
 TEST_GEN_FILES += hugetlb-madvise
diff --git a/tools/testing/selftests/mm/gup.c b/tools/testing/selftests/mm/gup.c
new file mode 100644
index 000000000000..a9b374b752df
--- /dev/null
+++ b/tools/testing/selftests/mm/gup.c
@@ -0,0 +1,341 @@
+// SPDX-License-Identifier: GPL-2.0
+#define __SANE_USERSPACE_TYPES__ // Use ll64
+#include <fcntl.h>
+#include <errno.h>
+#include <stdbool.h>
+#include <string.h>
+#include <unistd.h>
+#include <dirent.h>
+#include <sys/ioctl.h>
+#include <sys/mman.h>
+#include <mm/gup_test.h>
+#include "vm_util.h"
+#include "kselftest_harness.h"
+
+#define MB (1UL << 20)
+
+/* Just the flags we need, copied from the kernel internals. */
+#define FOLL_WRITE	0x01	/* check pte is writable */
+
+/* Page counts exercising single, THP-batch, partial, and full-mapping GUP. */
+static const int nr_pages_list[] = { 1, 512, 123, -1 };
+
+#define GUP_TEST_FILE "/sys/kernel/debug/gup_test"
+
+FIXTURE(gup_test)
+{
+	int gup_fd;
+	char *addr;
+	unsigned long size;
+};
+
+FIXTURE_VARIANT(gup_test)
+{
+	bool thp;
+	bool hugetlb;
+	bool write;
+	bool shared;
+};
+
+FIXTURE_VARIANT_ADD(gup_test, private_write)
+{
+	.thp = false,
+	.hugetlb = false,
+	.write = true,
+	.shared = false,
+};
+
+FIXTURE_VARIANT_ADD(gup_test, private_read)
+{
+	.thp = false,
+	.hugetlb = false,
+	.write = false,
+	.shared = false,
+};
+
+FIXTURE_VARIANT_ADD(gup_test, private_write_thp)
+{
+	.thp = true,
+	.hugetlb = false,
+	.write = true,
+	.shared = false,
+};
+
+FIXTURE_VARIANT_ADD(gup_test, private_read_thp)
+{
+	.thp = true,
+	.hugetlb = false,
+	.write = false,
+	.shared = false,
+};
+
+FIXTURE_VARIANT_ADD(gup_test, private_write_hugetlb)
+{
+	.thp = false,
+	.hugetlb = true,
+	.write = true,
+	.shared = false,
+};
+
+FIXTURE_VARIANT_ADD(gup_test, private_read_hugetlb)
+{
+	.thp = false,
+	.hugetlb = true,
+	.write = false,
+	.shared = false,
+};
+
+FIXTURE_VARIANT_ADD(gup_test, shared_write)
+{
+	.thp = false,
+	.hugetlb = false,
+	.write = true,
+	.shared = true,
+};
+
+FIXTURE_VARIANT_ADD(gup_test, shared_read)
+{
+	.thp = false,
+	.hugetlb = false,
+	.write = false,
+	.shared = true,
+};
+
+FIXTURE_VARIANT_ADD(gup_test, shared_write_thp)
+{
+	.thp = true,
+	.hugetlb = false,
+	.write = true,
+	.shared = true,
+};
+
+FIXTURE_VARIANT_ADD(gup_test, shared_read_thp)
+{
+	.thp = true,
+	.hugetlb = false,
+	.write = false,
+	.shared = true,
+};
+
+FIXTURE_VARIANT_ADD(gup_test, shared_write_hugetlb)
+{
+	.thp = false,
+	.hugetlb = true,
+	.write = true,
+	.shared = true,
+};
+
+FIXTURE_VARIANT_ADD(gup_test, shared_read_hugetlb)
+{
+	.thp = false,
+	.hugetlb = true,
+	.write = false,
+	.shared = true,
+};
+
+FIXTURE_SETUP(gup_test)
+{
+	int mmap_flags = MAP_PRIVATE;
+	int zero_fd;
+	char *p;
+
+	/* zero_fd has to be >= 0. Already checked in main() */
+	zero_fd = open("/dev/zero", O_RDWR);
+	ASSERT_GE(zero_fd, 0);
+
+	/* gup_fd has to be >= 0. Already checked in main() */
+	self->gup_fd = open(GUP_TEST_FILE, O_RDWR);
+	ASSERT_GE(self->gup_fd, 0);
+
+	self->size = variant->hugetlb ? 256 * MB : 128 * MB;
+
+	if (variant->hugetlb) {
+		unsigned long hp_size = default_huge_page_size();
+
+		if (!hp_size) {
+			close(zero_fd);
+			close(self->gup_fd);
+			SKIP(return, "HugeTLB not available\n");
+		}
+
+		self->size = (self->size + hp_size - 1) & ~(hp_size - 1);
+		if (!hugetlb_setup_default(self->size / hp_size)) {
+			hugetlb_restore_settings();
+			close(zero_fd);
+			close(self->gup_fd);
+			SKIP(return, "Not enough huge pages\n");
+		}
+
+		mmap_flags |= (MAP_HUGETLB | MAP_ANONYMOUS);
+	}
+
+	if (variant->shared)
+		mmap_flags = (mmap_flags & ~MAP_PRIVATE) | MAP_SHARED;
+
+	self->addr = mmap(NULL, self->size, PROT_READ | PROT_WRITE,
+			  mmap_flags, zero_fd, 0);
+
+	ASSERT_NE(self->addr, MAP_FAILED) {
+		int err = errno;
+
+		close(zero_fd);
+		close(self->gup_fd);
+		if (variant->hugetlb)
+			hugetlb_restore_settings();
+		TH_LOG("mmap failed: %s", strerror(err));
+	}
+	close(zero_fd);
+
+	if (variant->thp)
+		madvise(self->addr, self->size, MADV_HUGEPAGE);
+	else if (!variant->hugetlb)
+		madvise(self->addr, self->size, MADV_NOHUGEPAGE);
+
+	for (p = self->addr; (unsigned long)p < (unsigned long)self->addr
+			+ self->size; p += psize())
+		p[0] = 0;
+}
+
+FIXTURE_TEARDOWN(gup_test)
+{
+	munmap(self->addr, self->size);
+	close(self->gup_fd);
+
+	if (variant->hugetlb)
+		hugetlb_restore_settings();
+}
+
+static void run_gup_cmd(struct __test_metadata *_metadata,
+			 FIXTURE_DATA(gup_test) *self,
+			 const FIXTURE_VARIANT(gup_test) *variant,
+			 unsigned long command,
+			 unsigned int test_flags,
+			 unsigned int which_page)
+{
+	int i;
+
+	for (i = 0; i < (int)ARRAY_SIZE(nr_pages_list); i++) {
+		struct gup_test gup = {
+			.addr = (unsigned long)self->addr,
+			.size = self->size,
+			.nr_pages_per_call = nr_pages_list[i] < 0 ?
+				self->size / psize() : nr_pages_list[i],
+			.test_flags = test_flags,
+		};
+
+		if (variant->write)
+			gup.gup_flags |= FOLL_WRITE;
+
+		gup.which_pages[0] = which_page;
+
+		TH_LOG("nr_pages_per_call=%u", gup.nr_pages_per_call);
+		ASSERT_EQ(ioctl(self->gup_fd, command, &gup), 0);
+	}
+}
+
+TEST_F(gup_test, get_user_pages)
+{
+	run_gup_cmd(_metadata, self, variant, GUP_BASIC_TEST, 0, 0);
+}
+
+TEST_F(gup_test, pin_user_pages)
+{
+	run_gup_cmd(_metadata, self, variant, PIN_BASIC_TEST, 0, 0);
+}
+
+TEST_F(gup_test, dump_user_pages_with_get)
+{
+	run_gup_cmd(_metadata, self, variant, DUMP_USER_PAGES_TEST, 0, 1);
+}
+
+TEST_F(gup_test, dump_user_pages_with_pin)
+{
+	run_gup_cmd(_metadata, self, variant, DUMP_USER_PAGES_TEST,
+		    GUP_TEST_FLAG_DUMP_PAGES_USE_PIN, 1);
+}
+
+TEST_F(gup_test, get_user_pages_fast)
+{
+	run_gup_cmd(_metadata, self, variant, GUP_FAST_BENCHMARK, 0, 0);
+}
+
+TEST_F(gup_test, pin_user_pages_fast)
+{
+	run_gup_cmd(_metadata, self, variant, PIN_FAST_BENCHMARK, 0, 0);
+}
+
+TEST_F(gup_test, pin_user_pages_longterm)
+{
+	run_gup_cmd(_metadata, self, variant, PIN_LONGTERM_BENCHMARK, 0, 0);
+}
+
+TEST(dump_user_pages_sparse_indices)
+{
+	struct gup_test gup = { 0 };
+	unsigned long size = 128 * MB;
+	int zero_fd, gup_fd;
+	char *addr, *p;
+
+	zero_fd = open("/dev/zero", O_RDWR);
+	ASSERT_GE(zero_fd, 0);
+
+	gup_fd = open(GUP_TEST_FILE, O_RDWR);
+	ASSERT_GE(gup_fd, 0);
+
+	addr = mmap(NULL, size, PROT_READ | PROT_WRITE, MAP_PRIVATE, zero_fd, 0);
+	close(zero_fd);
+	ASSERT_NE(addr, MAP_FAILED);
+
+	madvise(addr, size, MADV_HUGEPAGE);
+
+	for (p = addr; (unsigned long)p < (unsigned long)addr + size;
+	     p += psize())
+		p[0] = 0;
+
+	gup.addr = (unsigned long)addr;
+	gup.size = size;
+	gup.nr_pages_per_call = size / psize();
+	gup.gup_flags = FOLL_WRITE;
+	gup.which_pages[0] = 1;
+	gup.which_pages[1] = 20;
+	gup.which_pages[2] = 0x1001;
+
+	ASSERT_EQ(ioctl(gup_fd, DUMP_USER_PAGES_TEST, &gup), 0);
+
+	munmap(addr, size);
+	close(gup_fd);
+}
+
+int main(int argc, char **argv)
+{
+	int fd;
+	char *file = "/dev/zero";
+
+	fd = open(file, O_RDWR);
+	if (fd < 0) {
+		ksft_print_header();
+		ksft_exit_fail_msg("Unable to open %s: %s\n", file, strerror(errno));
+	}
+	close(fd);
+
+	fd = open(GUP_TEST_FILE, O_RDWR);
+	if (fd == -1) {
+		ksft_print_header();
+		if (errno == EACCES)
+			ksft_exit_skip("Please run this test as root\n");
+		if (errno == ENOENT) {
+			DIR *debugfs = opendir("/sys/kernel/debug");
+
+			if (!debugfs) {
+				ksft_exit_skip("Mount debugfs at /sys/kernel/debug\n");
+			} else {
+				closedir(debugfs);
+				ksft_exit_skip("Check CONFIG_GUP_TEST in kernel config\n");
+			}
+		}
+		ksft_exit_fail_msg("Failed to open %s: %s\n", GUP_TEST_FILE, strerror(errno));
+	}
+	close(fd);
+
+	return test_harness_run(argc, argv);
+}
diff --git a/tools/testing/selftests/mm/run_vmtests.sh b/tools/testing/selftests/mm/run_vmtests.sh
index 263e4940cc1d..8cc4c8f403da 100755
--- a/tools/testing/selftests/mm/run_vmtests.sh
+++ b/tools/testing/selftests/mm/run_vmtests.sh
@@ -252,6 +252,7 @@ fi
 
 CATEGORY="mmap" run_test ./map_fixed_noreplace
 
+CATEGORY="gup_test" run_test ./gup
 CATEGORY="gup_test" run_test ./gup_longterm
 
 CATEGORY="userfaultfd" run_test ./uffd-unit-tests
-- 
2.39.5