vdso: dump -- Don't dump contents of vvar zone

vvar zone is mapped by a kernel and must not ever
been dumped into image, the data present there is
valid on running kernel only.
Signed-off-by: Cyrill Gorcunov <gorcunov@openvz.org>
Acked-by: Andrew Vagin <avagin@parallels.com>
Signed-off-by: Pavel Emelyanov <xemul@parallels.com>

cr-dump.c

@@ -94,6 +94,11 @@ bool privately_dump_vma(struct vma_area *vma)
 	if (vma->e->status & VMA_AREA_SYSVIPC)
 		return false;
 
+#ifdef CONFIG_VDSO
+	/* No dumps for vDSO VVAR data */
+	if (vma->e->status & VMA_AREA_VVAR)
+		return false;
+#endif
 	if (vma_area_is(vma, VMA_ANON_SHARED))
 		return false;
 

mem.c

@@ -67,8 +67,23 @@ unsigned int dump_pages_args_size(struct vm_area_list *vmas)
 
 static inline bool should_dump_page(VmaEntry *vmae, u64 pme)
 {
+#ifdef CONFIG_VDSO
+	/*
+	 * vDSO area must be always dumped because on restore
+	 * we might need to generate a proxy.
+	 */
 	if (vma_entry_is(vmae, VMA_AREA_VDSO))
 		return true;
+	/*
+	 * In turn VVAR area is special and referenced from
+	 * vDSO area by IP addressing (at least on x86) thus
+	 * never ever dump its content but always use one provided
+	 * by the kernel on restore, ie runtime VVAR area must
+	 * be remapped into proper place..
+	 */
+	if (vma_entry_is(vmae, VMA_AREA_VVAR))
+		return false;
+#endif
 	/*
 	 * Optimisation for private mapping pages, that haven't
 	 * yet being COW-ed