vdso: Introduce vdso mark v3

We need to place @rt_vvar_addr into vdso mark, as we don't know
the position of rt-vvar to be dropped on the following dumps.
I've renamed proxy_*_addr to orig_*_addr, as it looks more
describing.
orig_*_addr we need for marking those VMAs as accordingly,
so restorer would know what to do with them. Otherwise, it'll
think they are just regular vmas.
Signed-off-by: Dmitry Safonov <dsafonov@virtuozzo.com>
Signed-off-by: Andrei Vagin <avagin@virtuozzo.com>

criu/include/parasite-vdso.h

@@ -18,64 +18,69 @@ static inline bool vdso_symbol_empty(struct vdso_symbol *s)
 }
 
 /*
- * Special mark which allows to identify runtime vdso where
- * calls from proxy vdso are redirected. This mark usually
+ * Special mark which allows to identify runtime vdso (rt-vdso) where
+ * calls from proxy (original) vdso are redirected. This mark usually
  * placed at the start of vdso area where Elf header lives.
- * Since such runtime vdso is solevey used by proxy and
+ * Since such runtime vdso is solely used by the proxy and
  * nobody else is supposed to access it, it's more-less
  * safe to screw the Elf header with @signature and
- * @proxy_addr.
+ * vvar/vdso addresses for next dumping.
  *
- * The @proxy_addr deserves a few comments. When we redirect
- * the calls from proxy to runtime vdso, on next checkpoint
- * it won't be possible to find which VMA is proxy, thus
- * we save its address in the member.
+ * The @orig_addr deserves a few comments. When we redirect the calls
+ * from the original vdso to runtime vdso, on next checkpoint it won't
+ * be possible to find original vdso/vvar pair, thus we save their
+ * addresses in the member.
+ *
+ * As on the following dumps we need to drop rt-{vvar,vdso} pair
+ * from list of VMAs to save in images, we save rt-vvar address also.
  */
 struct vdso_mark {
 	u64			signature;
-	unsigned long		proxy_vdso_addr;
-
+	unsigned long		orig_vdso_addr;
 	unsigned long		version;
-
-	/*
-	 * In case of new vDSO format the VVAR area address
-	 * neeed for easier discovering where it lives without
-	 * relying on procfs output.
-	 */
-	unsigned long		proxy_vvar_addr;
+	unsigned long		orig_vvar_addr;
+	unsigned long		rt_vvar_addr;
 };
 
-#define VDSO_MARK_SIGNATURE	(0x6f73647675697263ULL)	/* Magic number (criuvdso) */
+#define VDSO_MARK_SIGNATURE_V1	(0x6f73647675697263ULL)	/* Magic number (criuvdso) */
 #define VDSO_MARK_SIGNATURE_V2	(0x4f53447675697263ULL)	/* Magic number (criuvDSO) */
-#define VDSO_MARK_CUR_VERSION	(2)
+#define VDSO_MARK_SIGNATURE_V3	(0x4f53447655495243ULL)	/* Magic number (CRIUvDSO) */
+#define VDSO_MARK_CUR_VERSION	(3)
 
-static inline void vdso_put_mark(void *where, unsigned long proxy_vdso_addr, unsigned long proxy_vvar_addr)
+static inline void vdso_put_mark(void *where, unsigned long rt_vvar_addr,
+		unsigned long orig_vdso_addr, unsigned long orig_vvar_addr)
 {
 	struct vdso_mark *m = where;
 
-	m->signature		= VDSO_MARK_SIGNATURE_V2;
-	m->proxy_vdso_addr	= proxy_vdso_addr;
+	m->signature		= VDSO_MARK_SIGNATURE_V3;
+	m->orig_vdso_addr	= orig_vdso_addr;
 	m->version		= VDSO_MARK_CUR_VERSION;
-	m->proxy_vvar_addr	= proxy_vvar_addr;
+	m->orig_vvar_addr	= orig_vvar_addr;
+	m->rt_vvar_addr		= rt_vvar_addr;
 }
 
 static inline bool is_vdso_mark(void *addr)
 {
 	struct vdso_mark *m = addr;
 
-	if (m->signature == VDSO_MARK_SIGNATURE_V2) {
-		/*
-		 * New format
-		 */
+	switch (m->signature) {
+	case VDSO_MARK_SIGNATURE_V3:
 		return true;
-	} else if (m->signature == VDSO_MARK_SIGNATURE) {
-		/*
-		 * Old format -- simply extend the mark up
-		 * to the version we support.
-		 */
-		vdso_put_mark(m, m->proxy_vdso_addr, VVAR_BAD_ADDR);
+	/*
+	 * Old formats -- simply extend the mark up
+	 * to the version we support.
+	 */
+	case VDSO_MARK_SIGNATURE_V2:
+		vdso_put_mark(m, VVAR_BAD_ADDR,
+				m->orig_vdso_addr, m->orig_vvar_addr);
+		return true;
+
+	case VDSO_MARK_SIGNATURE_V1:
+		vdso_put_mark(m, VVAR_BAD_ADDR,
+				m->orig_vdso_addr, VVAR_BAD_ADDR);
 		return true;
 	}
+
 	return false;
 }
 

criu/pie/parasite-vdso.c

@@ -193,15 +193,26 @@ static int remap_rt_vdso(VmaEntry *vma_vdso, VmaEntry *vma_vvar,
  */
 static int add_vdso_proxy(VmaEntry *vma_vdso, VmaEntry *vma_vvar,
 		struct vdso_symtable *sym_img, struct vdso_symtable *sym_rt,
-		unsigned long rt_vdso_addr, bool compat_vdso)
+		unsigned long vdso_rt_parked_at, bool compat_vdso)
 {
+	unsigned long rt_vvar_addr = vdso_rt_parked_at;
+	unsigned long rt_vdso_addr = vdso_rt_parked_at;
+	unsigned long orig_vvar_addr =
+		vma_vvar ? vma_vvar->start : VVAR_BAD_ADDR;
+
 	pr_info("Runtime vdso mismatches dumpee, generate proxy\n");
 
 	/*
 	 * Don't forget to shift if vvar is before vdso.
 	 */
-	if (sym_rt->vvar_size != VDSO_BAD_SIZE && !sym_rt->vdso_before_vvar)
-		rt_vdso_addr += sym_rt->vvar_size;
+	if (sym_rt->vvar_size == VVAR_BAD_SIZE) {
+		rt_vvar_addr = VVAR_BAD_ADDR;
+	} else {
+		if (sym_rt->vdso_before_vvar)
+			rt_vvar_addr += sym_rt->vdso_size;
+		else
+			rt_vdso_addr += sym_rt->vvar_size;
+	}
 
 	if (vdso_redirect_calls(rt_vdso_addr, vma_vdso->start,
 				sym_rt, sym_img, compat_vdso)) {
@@ -215,8 +226,8 @@ static int add_vdso_proxy(VmaEntry *vma_vdso, VmaEntry *vma_vvar,
 	 * it's auto-generated every new session if proxy required.
 	 */
 	sys_mprotect((void *)rt_vdso_addr,  sym_rt->vdso_size, PROT_WRITE);
-	vdso_put_mark((void *)rt_vdso_addr, vma_vdso->start,
-			vma_vvar ? vma_vvar->start : VVAR_BAD_ADDR);
+	vdso_put_mark((void *)rt_vdso_addr, rt_vvar_addr,
+			vma_vdso->start, orig_vvar_addr);
 	sys_mprotect((void *)rt_vdso_addr,  sym_rt->vdso_size, VDSO_PROT);
 
 	return 0;

criu/pie/parasite.c

@@ -555,8 +555,8 @@ static int parasite_check_vdso_mark(struct parasite_vdso_vma_entry *args)
 			return -EINVAL;
 		}
 		args->is_marked = 1;
-		args->proxy_vdso_addr = m->proxy_vdso_addr;
-		args->proxy_vvar_addr = m->proxy_vvar_addr;
+		args->proxy_vdso_addr = m->orig_vdso_addr;
+		args->proxy_vvar_addr = m->orig_vvar_addr;
 	} else {
 		args->is_marked = 0;
 		args->proxy_vdso_addr = VDSO_BAD_ADDR;