test/vdso-proxy: handle merged vma-s

When we compare two list of vma-s, we need to take into account that
some of them could be merged.

Fixes #12286

Signed-off-by: Andrei Vagin <avagin@google.com>

Author: avagin

test/zdtm/static/vdso-proxy.c

@@ -70,6 +70,7 @@ static int parse_maps(struct vm_area *vmas)
 #endif
 		v->is_vvar_or_vdso |= strstr(buf, "[vdso]") != NULL;
 		v->is_vvar_or_vdso |= strstr(buf, "[vvar]") != NULL;
+		v->is_vvar_or_vdso |= strstr(buf, "[vvar_vclock]") != NULL;
 		test_msg("[NOTE]\tVMA: [%#" PRIx64 ", %#" PRIx64 "]\n", v->start, v->end);
 	}
 
@@ -104,24 +105,30 @@ static int check_vvar_vdso(struct vm_area *before, struct vm_area *after)
 {
 	int i, j = 0;
 
-	for (i = 0; i < MAX_VMAS && j < MAX_VMAS; i++, j++) {
-		int cmp = compare_vmas(&before[i], &after[j]);
-
-		if (cmp == 0)
-			continue;
-
-		if (cmp < 0) { /* Lost mapping */
+	for (i = 0; i < MAX_VMAS && j < MAX_VMAS;) {
+		if (before[i].start < after[j].start) {
 			test_msg("[NOTE]\tLost mapping: %#" PRIx64 "-%#" PRIx64 "\n", before[i].start, before[i].end);
-			j--;
 			if (before[i].is_vvar_or_vdso) {
 				fail("Lost vvar/vdso mapping");
 				return -1;
 			}
+			i++;
 			continue;
 		}
-
-		test_msg("[NOTE]\tNew mapping appeared: %#" PRIx64 "-%#" PRIx64 "\n", after[j].start, after[j].end);
-		i--;
+		if (before[i].start > after[j].start) {
+			test_msg("[NOTE]\tNew mapping appeared: %#" PRIx64 "-%#" PRIx64 "\n", after[j].start, after[j].end);
+			j++;
+			continue;
+		}
+		if (before[i].end == after[j].end) {
+			i++; j++;
+		} else if (before[i].end > after[j].end) {
+			before[i].start = after[j].end;
+			j++;
+		} else {
+			after[j].start = before[i].end;
+			i++;
+		}
 	}
 
 	return 0;