auxv: save and restore AUXV's in a machine-independent way.

The size of an auxv is the machine pointer but a 64-bit integer is reserved
in a MmEntry protobuf message to store an auxv. Moreover the number of auxv's
varies from one architecture to another. So the following is proposed
to alleviate the issue.

* Introduced the type auxv_t representing a machine-pointer sized integer.

* The size of auxv array is extracted from a MmEntry message instead of using
  the value of the macro AT_VECTOR_SIZE.
Signed-off-by: Alexander Kartashov <alekskartashov@parallels.com>
Signed-off-by: Pavel Emelyanov <xemul@parallels.com>

arch/x86/include/asm/types.h

@@ -247,4 +247,6 @@ typedef struct {
 
 #define TASK_SIZE ((1UL << 47) - 1)
 
+typedef uint64_t auxv_t;
+
 #endif /* __CR_ASM_TYPES_H__ */

cr-dump.c

@@ -552,10 +552,10 @@ static int get_task_auxv(pid_t pid, MmEntry *mm, size_t *size)
 
 	for (i = 0; i < AT_VECTOR_SIZE; i++) {
 		ret = read(fd, &mm->mm_saved_auxv[i],
-			   sizeof(mm->mm_saved_auxv[0]));
+			   sizeof(auxv_t));
 		if (ret == 0)
 			break;
-		else if (ret != sizeof(mm->mm_saved_auxv[0])) {
+		else if (ret != sizeof(auxv_t)) {
 			ret = -1;
 			pr_perror("Error readind %d's auxv[%d]",
 				  pid, i);

cr-restore.c

@@ -1453,7 +1453,7 @@ static VmaEntry *vma_list_remap(void *addr, unsigned long len, struct list_head
 
 static int prepare_mm(pid_t pid, struct task_restore_core_args *args)
 {
-	int fd, exe_fd, ret = -1;
+	int fd, exe_fd, i, ret = -1;
 	MmEntry *mm;
 
 	fd = open_image_ro(CR_FD_MM, pid);
@@ -1474,9 +1474,10 @@ static int prepare_mm(pid_t pid, struct task_restore_core_args *args)
 		goto out;
 	}
 
-	args->mm_saved_auxv_size = pb_repeated_size(mm, mm_saved_auxv);
-	memcpy(args->mm_saved_auxv, mm->mm_saved_auxv,
-	       args->mm_saved_auxv_size);
+	args->mm_saved_auxv_size = mm->n_mm_saved_auxv*sizeof(auxv_t);
+	for (i = 0; i < mm->n_mm_saved_auxv; ++i) {
+		args->mm_saved_auxv[i] = (auxv_t)mm->mm_saved_auxv[i];
+	}
 
 	exe_fd = open_reg_by_id(args->mm.exe_file_id);
 	if (exe_fd < 0)

include/restorer.h

@@ -123,7 +123,7 @@ struct task_restore_core_args {
 	uint32_t			cap_bnd[CR_CAP_SIZE];
 
 	MmEntry				mm;
-	u64				mm_saved_auxv[AT_VECTOR_SIZE];
+	auxv_t				mm_saved_auxv[AT_VECTOR_SIZE];
 	u32				mm_saved_auxv_size;
 	char				comm[TASK_COMM_LEN];