init/bootconfig: Reorder init parameter from bootconfig and cmdline

Reorder the init parameters from bootconfig and kernel cmdline
so that the kernel cmdline always be the last part of the
parameters as below.

 " -- "[bootconfig init params][cmdline init params]

This change will help us to prevent that bootconfig init params
overwrite the init params which user gives in the command line.

Link: https://lkml.kernel.org/r/163077085675.222577.5665176468023636160.stgit@devnote2

Signed-off-by: Masami Hiramatsu <[email protected]>
Signed-off-by: Steven Rostedt (VMware) <[email protected]>

Author: mhiramat

init/main.c

@@ -153,10 +153,10 @@ static char *extra_init_args;
 #ifdef CONFIG_BOOT_CONFIG
 /* Is bootconfig on command line? */
 static bool bootconfig_found;
-static bool initargs_found;
+static size_t initargs_offs;
 #else
 # define bootconfig_found false
-# define initargs_found false
+# define initargs_offs 0
 #endif
 
 static char *execute_command;
@@ -422,9 +422,9 @@ static void __init setup_boot_config(void)
 	if (IS_ERR(err) || !bootconfig_found)
 		return;
 
-	/* parse_args() stops at '--' and returns an address */
+	/* parse_args() stops at the next param of '--' and returns an address */
 	if (err)
-		initargs_found = true;
+		initargs_offs = err - tmp_cmdline;
 
 	if (!data) {
 		pr_err("'bootconfig' found on command line, but no bootconfig found\n");
@@ -655,16 +655,21 @@ static void __init setup_command_line(char *command_line)
 		 * Append supplemental init boot args to saved_command_line
 		 * so that user can check what command line options passed
 		 * to init.
+		 * The order should always be
+		 * " -- "[bootconfig init-param][cmdline init-param]
 		 */
-		len = strlen(saved_command_line);
-		if (initargs_found) {
-			saved_command_line[len++] = ' ';
+		if (initargs_offs) {
+			len = xlen + initargs_offs;
+			strcpy(saved_command_line + len, extra_init_args);
+			len += ilen - 4;	/* strlen(extra_init_args) */
+			strcpy(saved_command_line + len,
+				boot_command_line + initargs_offs - 1);
 		} else {
+			len = strlen(saved_command_line);
 			strcpy(saved_command_line + len, " -- ");
 			len += 4;
+			strcpy(saved_command_line + len, extra_init_args);
 		}
-
-		strcpy(saved_command_line + len, extra_init_args);
 	}
 }