page-pipe: add compatible iovec

struct iovec may have different size for dumpee.
But that reason, pages dump will fail (with added debug to pie):
(00.011440) page-pipe: Page pipe:
(00.011441) page-pipe: * 1 pipes 8/523 iovs:
(00.011442) page-pipe: 	buf 16 pages, 8 iovs:
(00.011444) page-pipe: 		0x8048000 3
(00.011446) page-pipe: 		0xf7512000 1
(00.011447) page-pipe: 		0xf76ca000 4
(00.011449) page-pipe: 		0xf76cf000 1
(00.011450) page-pipe: 		0xf76dc000 2
(00.011452) page-pipe: 		0xf76e1000 1
(00.011454) page-pipe: 		0xf7702000 2
(00.011455) page-pipe: 		0xffdad000 2
(00.011470) page-pipe: * 0 holes:
(00.011471) PPB: 16 pages 8 segs 16 pipe 0 off
(00.011476) Sent msg to daemon 8 0 0
pie: __fetched msg: 8 0 0
(00.011479) Wait for ack 8 on daemon socket
pie: sys_vmsplice for 16 pages 8 segs 0 off
pie:  buf 16 pages, 8 iovs:
pie: 	0x8048000 0
pie: 	0x3000 0
pie: 	0xf7512000 0
pie: 	0x1000 0
pie: 	0xf76ca000 0
pie: 	0x4000 0
pie: 	0xf76cf000 0
pie: 	0x1000 0
pie: Error (pie/parasite.c:93): Can't splice pages to pipe (0/16)
pie: __sent ack msg: 8 8 -1

Cc: Cyrill Gorcunov <gorcunov@openvz.org>
Signed-off-by: Dmitry Safonov <dsafonov@virtuozzo.com>
Signed-off-by: Pavel Emelyanov <xemul@virtuozzo.com>
Signed-off-by: Andrei Vagin <avagin@virtuozzo.com>

criu/include/parasite-syscall.h

@@ -119,6 +119,7 @@ extern int syscall_seized(struct parasite_ctl *ctl, int nr, unsigned long *ret,
 extern int __parasite_execute_syscall(struct parasite_ctl *ctl,
 		user_regs_struct_t *regs, const char *code_syscall);
 extern bool arch_can_dump_task(struct parasite_ctl *ctl);
+extern bool seized_native(struct parasite_ctl *ctl);
 
 /*
  * The PTRACE_SYSCALL will trap task twice -- on

criu/mem.c

@@ -304,6 +304,8 @@ static int __parasite_dump_pages_seized(struct pstree_item *item,
 		 * use, i.e. on non-lazy non-predump.
 		 */
 		cpp_flags |= PP_CHUNK_MODE;
+	if (!seized_native(ctl))
+		cpp_flags |= PP_COMPAT;
 	pp = create_page_pipe(vma_area_list->priv_size,
 					    pargs_iovs(args), cpp_flags);
 	if (!pp)

criu/page-pipe.c

@@ -81,6 +81,18 @@ static int ppb_resize_pipe(struct page_pipe_buf *ppb, unsigned long new_size)
 	return 0;
 }
 
+/* XXX: move to arch-depended file, when non-x86 add support for compat mode */
+struct iovec_compat {
+	u32	iov_base;
+	u32	iov_len;
+};
+
+static inline void iov_init_compat(struct iovec_compat *iov, unsigned long addr)
+{
+	iov->iov_base = (u32)addr;
+	iov->iov_len = PAGE_SIZE;
+}
+
 static int page_pipe_grow(struct page_pipe *pp)
 {
 	struct page_pipe_buf *ppb;
@@ -208,7 +220,13 @@ static inline int try_add_page_to(struct page_pipe *pp, struct page_pipe_buf *pp
 
 	pr_debug("Add iov to page pipe (%u iovs, %u/%u total)\n",
 			ppb->nr_segs, pp->free_iov, pp->nr_iovs);
+	if (pp->flags & PP_COMPAT) {
+		struct iovec_compat *iovs = (void *)ppb->iov;
+
+		iov_init_compat(&iovs[ppb->nr_segs++], addr);
+	} else {
 		iov_init(&ppb->iov[ppb->nr_segs++], addr);
+	}
 	pp->free_iov++;
 	BUG_ON(pp->free_iov > pp->nr_iovs);
 out:
@@ -256,7 +274,13 @@ int page_pipe_add_hole(struct page_pipe *pp, unsigned long addr)
 			iov_grow_page(&pp->holes[pp->free_hole - 1], addr))
 		goto out;
 
+	if (pp->flags & PP_COMPAT) {
+		struct iovec_compat *iovs = (void *)pp->holes;
+
+		iov_init_compat(&iovs[pp->free_hole++], addr);
+	} else {
 		iov_init(&pp->holes[pp->free_hole++], addr);
+	}
 out:
 	return 0;
 }
@@ -266,6 +290,7 @@ void debug_show_page_pipe(struct page_pipe *pp)
 	struct page_pipe_buf *ppb;
 	int i;
 	struct iovec *iov;
+	struct iovec_compat *iov_c;
 
 	if (pr_quelled(LOG_DEBUG))
 		return;
@@ -277,14 +302,28 @@ void debug_show_page_pipe(struct page_pipe *pp)
 		pr_debug("\tbuf %u pages, %u iovs:\n",
 				ppb->pages_in, ppb->nr_segs);
 		for (i = 0; i < ppb->nr_segs; i++) {
+			if (pp->flags & PP_COMPAT) {
+				iov_c = (void *)ppb->iov;
+				pr_debug("\t\t%x %lu\n", iov_c[i].iov_base,
+						iov_c[i].iov_len / PAGE_SIZE);
+			} else {
 				iov = &ppb->iov[i];
-			pr_debug("\t\t%p %lu\n", iov->iov_base, iov->iov_len / PAGE_SIZE);
+				pr_debug("\t\t%p %lu\n", iov->iov_base,
+						iov->iov_len / PAGE_SIZE);
+			}
 		}
 	}
 
 	pr_debug("* %u holes:\n", pp->free_hole);
 	for (i = 0; i < pp->free_hole; i++) {
+		if (pp->flags & PP_COMPAT) {
+			iov_c = (void *)pp->holes;
+			pr_debug("\t%x %lu\n", iov_c[i].iov_base,
+					iov_c[i].iov_len / PAGE_SIZE);
+		} else {
 			iov = &pp->holes[i];
-		pr_debug("\t%p %lu\n", iov->iov_base, iov->iov_len / PAGE_SIZE);
+			pr_debug("\t%p %lu\n", iov->iov_base,
+					iov->iov_len / PAGE_SIZE);
+		}
 	}
 }

criu/parasite-syscall.c

@@ -120,7 +120,7 @@ static int restore_thread_ctx(int pid, struct thread_ctx *ctx)
 	return ret;
 }
 
-static inline bool seized_native(struct parasite_ctl *ctl)
+bool seized_native(struct parasite_ctl *ctl)
 {
 	return user_regs_native(&ctl->orig.regs);
 }