1 files changed, 63 insertions, 4 deletions

diff --git a/tools/testing/selftests/x86/test_shadow_stack.c b/tools/testing/selftests/x86/test_shadow_stack.c
index 757e6527f67e..ee909a7927f9 100644
--- a/tools/testing/selftests/x86/test_shadow_stack.c
+++ b/tools/testing/selftests/x86/test_shadow_stack.c
@@ -556,7 +556,7 @@ struct node {
  *      looked at the shadow stack gaps.
  *   5. See if it landed in the gap.
  */
-int test_guard_gap(void)
+int test_guard_gap_other_gaps(void)
 {
 	void *free_area, *shstk, *test_map = (void *)0xFFFFFFFFFFFFFFFF;
 	struct node *head = NULL, *cur;
@@ -593,11 +593,64 @@ int test_guard_gap(void)
 	if (shstk - test_map - PAGE_SIZE != PAGE_SIZE)
 		return 1;
 
-	printf("[OK]\tGuard gap test\n");
+	printf("[OK]\tGuard gap test, other mapping's gaps\n");
 
 	return 0;
 }
 
+/* Tests respecting the guard gap of the mapping getting placed */
+int test_guard_gap_new_mappings_gaps(void)
+{
+	void *free_area, *shstk_start, *test_map = (void *)0xFFFFFFFFFFFFFFFF;
+	struct node *head = NULL, *cur;
+	int ret = 0;
+
+	free_area = mmap(0, PAGE_SIZE * 4, PROT_READ | PROT_WRITE,
+			 MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);
+	munmap(free_area, PAGE_SIZE * 4);
+
+	/* Test letting map_shadow_stack find a free space */
+	shstk_start = mmap(free_area, PAGE_SIZE, PROT_READ | PROT_WRITE,
+			   MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);
+	if (shstk_start == MAP_FAILED || shstk_start != free_area)
+		return 1;
+
+	while (test_map > shstk_start) {
+		test_map = (void *)syscall(__NR_map_shadow_stack, 0, PAGE_SIZE, 0);
+		if (test_map == MAP_FAILED) {
+			printf("[INFO]\tmap_shadow_stack MAP_FAILED\n");
+			ret = 1;
+			break;
+		}
+
+		cur = malloc(sizeof(*cur));
+		cur->mapping = test_map;
+
+		cur->next = head;
+		head = cur;
+
+		if (test_map == free_area + PAGE_SIZE) {
+			printf("[INFO]\tNew mapping has other mapping in guard gap!\n");
+			ret = 1;
+			break;
+		}
+	}
+
+	while (head) {
+		cur = head;
+		head = cur->next;
+		munmap(cur->mapping, PAGE_SIZE);
+		free(cur);
+	}
+
+	munmap(shstk_start, PAGE_SIZE);
+
+	if (!ret)
+		printf("[OK]\tGuard gap test, placement mapping's gaps\n");
+
+	return ret;
+}
+
 /*
  * Too complicated to pull it out of the 32 bit header, but also get the
  * 64 bit one needed above. Just define a copy here.
@@ -850,9 +903,15 @@ int main(int argc, char *argv[])
 		goto out;
 	}
 
-	if (test_guard_gap()) {
+	if (test_guard_gap_other_gaps()) {
+		ret = 1;
+		printf("[FAIL]\tGuard gap test, other mappings' gaps\n");
+		goto out;
+	}
+
+	if (test_guard_gap_new_mappings_gaps()) {
 		ret = 1;
-		printf("[FAIL]\tGuard gap test\n");
+		printf("[FAIL]\tGuard gap test, placement mapping's gaps\n");
 		goto out;
 	}