From: Andrei Vagin <avagin@xxxxxxxxx>
Add a selftest to verify the PAGEMAP_SCAN ioctl correctly reports guard
regions using the newly introduced PAGE_IS_GUARD flag.
Signed-off-by: Andrei Vagin <avagin@xxxxxxxxx>
---
tools/testing/selftests/mm/guard-regions.c | 53 ++++++++++++++++++++++
1 file changed, 53 insertions(+)
diff --git a/tools/testing/selftests/mm/guard-regions.c b/tools/testing/selftests/mm/guard-regions.c
index 0c7183e8b661..24e09092fda5 100644
--- a/tools/testing/selftests/mm/guard-regions.c
+++ b/tools/testing/selftests/mm/guard-regions.c
@@ -8,6 +8,7 @@
#include <fcntl.h>
#include <linux/limits.h>
#include <linux/userfaultfd.h>
+#include <linux/fs.h>
#include <setjmp.h>
#include <signal.h>
#include <stdbool.h>
@@ -2079,4 +2080,56 @@ TEST_F(guard_regions, pagemap)
ASSERT_EQ(munmap(ptr, 10 * page_size), 0);
}
+/*
+ * Assert that PAGEMAP_SCAN correctly reports guard region ranges.
+ */
+TEST_F(guard_regions, pagemap_scan)
+{
+ const unsigned long page_size = self->page_size;
+ struct page_region pm_regs[10];
+ struct pm_scan_arg pm_scan_args = {
+ .size = sizeof(struct pm_scan_arg),
+ .category_anyof_mask = PAGE_IS_GUARD,
+ .return_mask = PAGE_IS_GUARD,
+ .vec = (long)&pm_regs,
+ .vec_len = ARRAY_SIZE(pm_regs),
+ };
+ int proc_fd, i;
+ char *ptr;
+
+ proc_fd = open("/proc/self/pagemap", O_RDONLY);
+ ASSERT_NE(proc_fd, -1);
+
+ ptr = mmap_(self, variant, NULL, 10 * page_size,
+ PROT_READ | PROT_WRITE, 0, 0);
+ ASSERT_NE(ptr, MAP_FAILED);
+
+ pm_scan_args.start = (long)ptr;
+ pm_scan_args.end = (long)ptr + 10 * page_size;
+ ASSERT_EQ(ioctl(proc_fd, PAGEMAP_SCAN, &pm_scan_args), 0);
+ ASSERT_EQ(pm_scan_args.walk_end, (long)ptr + 10 * page_size);
+
+ /* Install a guard region in every other page. */
+ for (i = 0; i < 10; i += 2) {
+ char *ptr_p = &ptr[i * page_size];
+
+ ASSERT_EQ(syscall(__NR_madvise, ptr_p, page_size, MADV_GUARD_INSTALL), 0);
+ }
+
+ ASSERT_EQ(ioctl(proc_fd, PAGEMAP_SCAN, &pm_scan_args), 5);
+ ASSERT_EQ(pm_scan_args.walk_end, (long)ptr + 10 * page_size);
+
+ /* Re-read from pagemap, and assert guard regions are detected. */
+ for (i = 0; i < 5; i++) {
+ long ptr_p = (long)&ptr[2 * i * page_size];
+
+ ASSERT_EQ(pm_regs[i].start, ptr_p);
+ ASSERT_EQ(pm_regs[i].end, ptr_p + page_size);
+ ASSERT_EQ(pm_regs[i].categories, PAGE_IS_GUARD);
+ }
+
+ ASSERT_EQ(close(proc_fd), 0);
+ ASSERT_EQ(munmap(ptr, 10 * page_size), 0);
+}
+
TEST_HARNESS_MAIN
--
2.49.0.rc1.451.g8f38331e32-goog
