vdso: Split parasite_fixup_vdso() once more

It's hard to stop, when you've begun.
No functional change is expected.
Signed-off-by: Dmitry Safonov <dsafonov@virtuozzo.com>
Signed-off-by: Andrei Vagin <avagin@virtuozzo.com>

criu/vdso.c

@@ -113,9 +113,16 @@ static bool not_vvar_or_vdso(struct vma_area *vma)
 	return false;
 }
 
+/* Contains addresses from vdso mark */
+struct vdso_quarter {
+	unsigned long orig_vdso;
+	unsigned long orig_vvar;
+	unsigned long rt_vdso;
+	unsigned long rt_vvar;
+};
+
 static void drop_rt_vdso(struct vm_area_list *vma_area_list,
-	unsigned long orig_vdso_addr, unsigned long orig_vvar_addr,
-	unsigned long rt_vvar_addr, struct vma_area *rt_vdso_marked)
+	struct vdso_quarter *addr, struct vma_area *rt_vdso_marked)
 {
 	struct vma_area *rt_vvar_marked = NULL;
 	struct vma_area *vma;
@@ -128,7 +135,7 @@ static void drop_rt_vdso(struct vm_area_list *vma_area_list,
 	 * and must be dropped from vma list.
 	 */
 	pr_debug("vdso: Found marked at %lx (orig vDSO at %lx VVAR at %lx)\n",
-		(long)rt_vdso_marked->e->start, orig_vdso_addr, orig_vvar_addr);
+		(long)rt_vdso_marked->e->start, addr->orig_vdso, addr->orig_vvar);
 
 	/*
 	 * Don't forget to restore the proxy vdso/vvar status, since
@@ -136,16 +143,16 @@ static void drop_rt_vdso(struct vm_area_list *vma_area_list,
 	 * Also BTW search for rt-vvar to remove it later.
 	 */
 	list_for_each_entry(vma, &vma_area_list->h, list) {
-		if (vma->e->start == orig_vdso_addr) {
+		if (vma->e->start == addr->orig_vdso) {
 			vma->e->status |= VMA_AREA_REGULAR | VMA_AREA_VDSO;
 			pr_debug("vdso: Restore orig vDSO status at %lx\n",
 					(long)vma->e->start);
-		} else if (vma->e->start == orig_vvar_addr) {
+		} else if (vma->e->start == addr->orig_vvar) {
 			vma->e->status |= VMA_AREA_REGULAR | VMA_AREA_VVAR;
 			pr_debug("vdso: Restore orig VVAR status at %lx\n",
 					(long)vma->e->start);
-		} else if (rt_vvar_addr != VVAR_BAD_ADDR &&
-				rt_vvar_addr == vma->e->start) {
+		} else if (addr->rt_vvar != VVAR_BAD_ADDR &&
+				addr->rt_vvar == vma->e->start) {
 			BUG_ON(rt_vvar_marked);
 			if (not_vvar_or_vdso(vma)) {
 				pr_warn("Mark in rt-vdso points to vma, that doesn't look like vvar - skipping unmap\n");
@@ -171,50 +178,29 @@ static void drop_rt_vdso(struct vm_area_list *vma_area_list,
 }
 
 /*
- * The VMAs list might have proxy vdso/vvar areas left
- * from previous dump/restore cycle so we need to detect
- * them and eliminated from the VMAs list, they will be
- * generated again on restore if needed.
+ * I need to poke every potentially marked vma,
+ * otherwise if task never called for vdso functions
+ * page frame number won't be reported.
+ *
+ * Moreover, if page frame numbers are not accessible
+ * we have to scan the vma zone for vDSO elf structure
+ * which gonna be a slow way.
  */
-int parasite_fixup_vdso(struct parasite_ctl *ctl, pid_t pid,
-			struct vm_area_list *vma_area_list)
+static int check_if_vma_is_vdso(enum vdso_check_t vcheck, int pagemap_fd,
+	struct parasite_ctl *ctl, struct vma_area *vma,
+	struct vma_area **rt_vdso_marked, struct vdso_quarter *addr)
 {
-	unsigned long orig_vdso_addr = VDSO_BAD_ADDR;
-	unsigned long orig_vvar_addr = VVAR_BAD_ADDR;
-	unsigned long rt_vvar_addr = VVAR_BAD_ADDR;
-	struct vma_area *rt_vdso_marked = NULL;
 	struct parasite_vdso_vma_entry *args;
-	int fd = -1, exit_code = -1;
-	enum vdso_check_t vcheck;
-	struct vma_area *vma;
+	bool has_vdso_pfn = false;
 
-	vcheck = get_vdso_check_type(ctl);
 	args = compel_parasite_args(ctl, struct parasite_vdso_vma_entry);
-	if (vcheck == VDSO_CHECK_PFN) {
-		BUG_ON(vdso_pfn == VDSO_BAD_PFN);
-		fd = open_proc(pid, "pagemap");
-		if (fd < 0)
-			return -1;
-	}
-
-	list_for_each_entry(vma, &vma_area_list->h, list) {
-		bool has_vdso_pfn = false;
 
 	if (not_vvar_or_vdso(vma))
-			continue;
+		return 0;
 
 	if ((vma->e->prot & VDSO_PROT) != VDSO_PROT)
-			continue;
+		return 0;
 
-		/*
-		 * I need to poke every potentially marked vma,
-		 * otherwise if task never called for vdso functions
-		 * page frame number won't be reported.
-		 *
-		 * Moreover, if page frame numbers are not accessible
-		 * we have to scan the vma zone for vDSO elf structure
-		 * which gonna be a slow way.
-		 */
 	args->start = vma->e->start;
 	args->len = vma_area_len(vma);
 	args->try_fill_symtable = (vcheck == VDSO_CHECK_SYMS);
@@ -222,32 +208,29 @@ int parasite_fixup_vdso(struct parasite_ctl *ctl, pid_t pid,
 
 	if (compel_rpc_call_sync(PARASITE_CMD_CHECK_VDSO_MARK, ctl)) {
 		pr_err("Parasite failed to poke for mark\n");
-			goto err;
+		return -1;
 	}
 
-		/*
-		 * Defer handling marked vdso until we walked over
-		 * all vmas and restore potentially remapped vDSO
-		 * area status.
-		 */
 	if (unlikely(args->is_marked)) {
-			if (rt_vdso_marked) {
+		if (*rt_vdso_marked) {
 			pr_err("Ow! Second vdso mark detected!\n");
-				goto err;
+			return -1;
 		}
-			rt_vdso_marked	= vma;
-			orig_vdso_addr	= args->orig_vdso_addr;
-			orig_vvar_addr	= args->orig_vvar_addr;
-			rt_vvar_addr	= args->rt_vvar_addr;
-			continue;
+		*rt_vdso_marked	= vma;
+		addr->orig_vdso	= args->orig_vdso_addr;
+		addr->orig_vvar	= args->orig_vvar_addr;
+		addr->rt_vvar	= args->rt_vvar_addr;
+		return 0;
 	}
 
 	if (vcheck == VDSO_NO_CHECK)
-			continue;
+		return 0;
 
-		if (vcheck == VDSO_CHECK_PFN && check_vdso_by_pfn(fd, vma, &has_vdso_pfn) < 0) {
-			pr_err("Failed checking vdso by pfn for %d\n", pid);
-			goto err;
+	if (vcheck == VDSO_CHECK_PFN) {
+		if (check_vdso_by_pfn(pagemap_fd, vma, &has_vdso_pfn) < 0) {
+			pr_err("Failed checking vdso by pfn\n");
+			return -1;
+		}
 	}
 
 	if (has_vdso_pfn || args->is_vdso) {
@@ -263,14 +246,55 @@ int parasite_fixup_vdso(struct parasite_ctl *ctl, pid_t pid,
 			vma->e->status &= ~VMA_AREA_VDSO;
 		}
 	}
+
+	return 0;
+}
+
+/*
+ * The VMAs list might have proxy vdso/vvar areas left
+ * from previous dump/restore cycle so we need to detect
+ * them and eliminated from the VMAs list, they will be
+ * generated again on restore if needed.
+ */
+int parasite_fixup_vdso(struct parasite_ctl *ctl, pid_t pid,
+			struct vm_area_list *vma_area_list)
+{
+	struct vma_area *rt_vdso_marked = NULL;
+	struct vdso_quarter addr = {
+		.orig_vdso = VDSO_BAD_ADDR,
+		.orig_vvar = VVAR_BAD_ADDR,
+		.rt_vdso = VDSO_BAD_ADDR,
+		.rt_vvar = VVAR_BAD_ADDR,
+	};
+	enum vdso_check_t vcheck;
+	struct vma_area *vma;
+	int fd = -1;
+
+	vcheck = get_vdso_check_type(ctl);
+	if (vcheck == VDSO_CHECK_PFN) {
+		BUG_ON(vdso_pfn == VDSO_BAD_PFN);
+		fd = open_proc(pid, "pagemap");
+		if (fd < 0)
+			return -1;
 	}
 
-	drop_rt_vdso(vma_area_list, orig_vdso_addr, orig_vvar_addr,
-			rt_vvar_addr, rt_vdso_marked);
-	exit_code = 0;
-err:
+	list_for_each_entry(vma, &vma_area_list->h, list) {
+		/*
+		 * Defer handling marked vdso until we walked over
+		 * all vmas and restore potentially remapped vDSO
+		 * area status.
+		 */
+		if (check_if_vma_is_vdso(vcheck, fd, ctl, vma,
+					&rt_vdso_marked, &addr)) {
 			close_safe(&fd);
-	return exit_code;
+			return -1;
+		}
+	}
+
+	drop_rt_vdso(vma_area_list, &addr, rt_vdso_marked);
+
+	close_safe(&fd);
+	return 0;
 }
 
 static int vdso_parse_maps(pid_t pid, struct vdso_maps *s)