restore: Add restore_core_args facility

More convenient instead of manual offset calculations.
Signed-off-by: Cyrill Gorcunov <gorcunov@gmail.com>

cr-restore.c

@@ -1221,25 +1221,31 @@ static int restore_all_tasks(pid_t pid)
 static void restorer_test(pid_t pid)
 {
 	restorer_fcall_t restorer_fcall;
+	struct restore_core_args *args;
 	char path[64];
 	void *args_rip;
 	void *exec_mem;
 	long ret;
 
+	/* VMA we need to run restorer code */
 	exec_mem = mmap(0, RESTORER_SIZE, PROT_READ | PROT_WRITE | PROT_EXEC, MAP_PRIVATE | MAP_ANON, 0, 0);
 	if (exec_mem == MAP_FAILED) {
 		pr_err("Can't mmap exec\n");
 		return;
 	}
 
+	/* Restorer content at the new location */
 	memcpy(exec_mem, &restorer, RESTORER_SIZE);
 	restorer_fcall = exec_mem;
-	restorer_fcall(RESTORER_CMD__GET_ARG_OFFSET);
-
-	args_rip = (void *)restorer_fcall(RESTORER_CMD__GET_ARG_OFFSET);
 
+	/*
+	 * Pass arguments and run a command.
+	 */
 	snprintf(path, sizeof(path), "core-%d.img", pid);
-	strcpy(args_rip, path);
+	args			= (struct restore_core_args *)restorer_fcall(RESTORER_CMD__GET_ARG_OFFSET);
+	args->self_entry	= exec_mem;
+	args->self_size		= RESTORER_SIZE;
+	strcpy(args->core_path, path);
 
 	ret = restorer_fcall(RESTORER_CMD__RESTORE_CORE);
 	pr_info("RESTORER_CMD__RESTORE_CORE: %lx\n", ret);

include/restorer.h

@@ -20,6 +20,12 @@ enum {
 	RESTORER_CMD__MAX,
 };
 
+struct restore_core_args {
+	void	*self_entry;	/* restorer placed at */
+	long	self_size;	/* size for restorer granted */
+	char	core_path[0];	/* path to a core file */
+};
+
 struct rt_sigframe {
 	char			*pretcode;
 	struct ucontext		uc;

restorer.c

@@ -76,18 +76,21 @@ long restorer(long cmd)
 	 */
 	case RESTORER_CMD__RESTORE_CORE:
 	{
-		char *core_path;
+		struct restore_core_args *args;
 		int fd_core;
 
 		struct core_entry core_entry;
+		struct vma_entry vma_entry;
+		u64 va;
+
 		struct rt_sigframe *frame;
 
-		lea_args_off(core_path);
+		lea_args_off(args);
 
-		write_string(core_path);
+		write_string(args->core_path);
 		write_string("\n");
 
-		fd_core = sys_open(core_path, O_RDONLY, CR_FD_PERM);
+		fd_core = sys_open(args->core_path, O_RDONLY, CR_FD_PERM);
 		if (fd_core < 0)
 			return fd_core;