vdso: handle vvar_vclock vma-s

The vvar_vclock was introduced by [1]. Basically, the old vvar vma has
been splited on two parts. In term of C/R, these two vma-s can be still
treated as one.

[1] e93d2521b27f ("x86/vdso: Split virtual clock pages into dedicated mapping")

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

criu/include/util-vdso.h

@@ -30,6 +30,7 @@ struct vdso_symbol {
 struct vdso_symtable {
 	unsigned long vdso_size;
 	unsigned long vvar_size;
+	unsigned long vvar_vclock_size;
 	struct vdso_symbol symbols[VDSO_SYMBOL_MAX];
 	bool vdso_before_vvar; /* order of vdso/vvar pair */
 };

criu/pie/parasite-vdso.c

@@ -45,6 +45,7 @@ static int remap_one(char *who, unsigned long *from, unsigned long to, size_t si
 static int park_at(struct vdso_maps *rt, unsigned long vdso, unsigned long vvar)
 {
 	unsigned long vvar_size = rt->sym.vvar_size;
+	unsigned long vvar_vclock_size = rt->sym.vvar_vclock_size;
 	unsigned long vdso_size = rt->sym.vdso_size;
 	int ret;
 
@@ -54,8 +55,24 @@ static int park_at(struct vdso_maps *rt, unsigned long vdso, unsigned long vvar)
 
 	std_log_set_gettimeofday(NULL); /* stop using vdso for timings */
 
-	if (vvar)
+	if (vvar) {
+		/*
+		 * v6.13-rc1~172^2~9 splits the vvar vma in two parts vvar and
+		 * vvar_clock. The last one is mapped right after the first
+		 * one.
+		 */
+		if (vvar_vclock_size) {
+			unsigned long from;
+
+			vvar_size -= vvar_vclock_size;
+			from = rt->vvar_start + vvar_size;
+
+			ret = remap_one("rt-vvar", &from, vvar + vvar_size, vvar_vclock_size);
+			if (ret)
+				return ret;
+		}
 		ret = remap_one("rt-vvar", &rt->vvar_start, vvar, vvar_size);
+	}
 
 	if (!ret)
 		vdso_update_gtod_addr(rt);

criu/proc_parse.c

@@ -579,7 +579,8 @@ static int handle_vma(pid_t pid, struct vma_area *vma_area, const char *file_pat
 	} else if (!strcmp(file_path, "[vdso]")) {
 		if (handle_vdso_vma(vma_area))
 			goto err;
-	} else if (!strcmp(file_path, "[vvar]")) {
+	} else if (!strcmp(file_path, "[vvar]") ||
+		   !strcmp(file_path, "[vvar_vclock]")) {
 		if (handle_vvar_vma(vma_area))
 			goto err;
 	} else if (!strcmp(file_path, "[heap]")) {
@@ -771,7 +772,7 @@ static int task_size_check(pid_t pid, VmaEntry *entry)
 
 int parse_smaps(pid_t pid, struct vm_area_list *vma_area_list, dump_filemap_t dump_filemap)
 {
-	struct vma_area *vma_area = NULL;
+	struct vma_area *vma_area = NULL, *prev_vma_area = NULL;
 	unsigned long start, end, pgoff, prev_end = 0;
 	char r, w, x, s;
 	int ret = -1, vm_file_fd = -1;
@@ -813,8 +814,22 @@ int parse_smaps(pid_t pid, struct vm_area_list *vma_area_list, dump_filemap_t du
 				continue;
 		}
 
-		if (vma_area && vma_list_add(vma_area, vma_area_list, &prev_end, &vfi, &prev_vfi))
-			goto err;
+		if (vma_area && vma_area_is(vma_area, VMA_AREA_VVAR) &&
+		    prev_vma_area && vma_area_is(prev_vma_area, VMA_AREA_VVAR)) {
+			if (prev_vma_area->e->end != vma_area->e->start) {
+				pr_err("two nonconsecutive vvar vma-s: "
+				       "%" PRIx64 "-%" PRIx64 " %" PRIx64 "-%" PRIx64 "\n",
+				       prev_vma_area->e->start, prev_vma_area->e->end,
+				       vma_area->e->start, vma_area->e->end);
+				goto err;
+			}
+			/* Merge all vvar vma-s into one. */
+			prev_vma_area->e->end = vma_area->e->end;
+		} else {
+			if (vma_area && vma_list_add(vma_area, vma_area_list, &prev_end, &vfi, &prev_vfi))
+				goto err;
+			prev_vma_area = vma_area;
+		}
 
 		if (eof)
 			break;

criu/vdso.c

@@ -310,7 +310,7 @@ static int vdso_parse_maps(pid_t pid, struct vdso_maps *s)
 
 	while (1) {
 		unsigned long start, end;
-		char *has_vdso, *has_vvar;
+		char *has_vdso, *has_vvar, *has_vvar_vclock;
 
 		buf = breadline(&f);
 		if (buf == NULL)
@@ -318,13 +318,19 @@ static int vdso_parse_maps(pid_t pid, struct vdso_maps *s)
 		if (IS_ERR(buf))
 			goto err;
 
-		has_vdso = strstr(buf, "[vdso]");
-		if (!has_vdso)
+		has_vvar = NULL;
+		has_vvar_vclock = NULL;
+		do {
+			has_vdso = strstr(buf, "[vdso]");
+			if (has_vdso)
+				break;
 			has_vvar = strstr(buf, "[vvar]");
-		else
-			has_vvar = NULL;
+			if (has_vvar)
+				break;
+			has_vvar_vclock = strstr(buf, "[vvar_vclock]");
+		} while (0);
 
-		if (!has_vdso && !has_vvar)
+		if (!has_vdso && !has_vvar && !has_vvar_vclock)
 			continue;
 
 		if (sscanf(buf, "%lx-%lx", &start, &end) != 2) {
@@ -339,13 +345,21 @@ static int vdso_parse_maps(pid_t pid, struct vdso_maps *s)
 			}
 			s->vdso_start = start;
 			s->sym.vdso_size = end - start;
-		} else {
+		} else if (has_vvar) {
 			if (s->vvar_start != VVAR_BAD_ADDR) {
 				pr_err("Got second VVAR entry\n");
 				goto err;
 			}
 			s->vvar_start = start;
 			s->sym.vvar_size = end - start;
+		} else {
+			if (s->vvar_start == VDSO_BAD_ADDR ||
+			    s->vvar_start + s->sym.vvar_size != start) {
+				pr_err("VVAR and VVAR_VCLOCK entries are not subsequent\n");
+				goto err;
+			}
+			s->sym.vvar_vclock_size = end - start;
+			s->sym.vvar_size += s->sym.vvar_vclock_size;
 		}
 	}