main: Make the execution path a little clearer in main.c

bootdelay_process() never returns in some circumstances, whichs makes the
control flow confusing. Change it so that the decision about how to execute
the boot command is made in the main_loop() code, so it is easier to follow.
Move CLI stuff to cli.c.

Signed-off-by: Simon Glass <sjg@chromium.org>

common/autoboot.c

@@ -22,6 +22,9 @@ DECLARE_GLOBAL_DATA_PTR;
 #define debug_bootkeys(fmt, args...)		\
 	debug_cond(DEBUG_BOOTKEYS, fmt, ##args)
 
+/* Stored value of bootdelay, used by autoboot_command() */
+static int stored_bootdelay;
+
 /***************************************************************************
  * Watch for 'delay' seconds for autoboot stop or autoboot delay string.
  * returns: 0 -  no key string, allow autoboot 1 - got key string, abort
@@ -205,57 +208,9 @@ static int abortboot(int bootdelay)
 #endif
 }
 
-/*
- * Runs the given boot command securely.  Specifically:
- * - Doesn't run the command with the shell (run_command or parse_string_outer),
- *   since that's a lot of code surface that an attacker might exploit.
- *   Because of this, we don't do any argument parsing--the secure boot command
- *   has to be a full-fledged u-boot command.
- * - Doesn't check for keypresses before booting, since that could be a
- *   security hole; also disables Ctrl-C.
- * - Doesn't allow the command to return.
- *
- * Upon any failures, this function will drop into an infinite loop after
- * printing the error message to console.
- */
-
-#if defined(CONFIG_OF_CONTROL)
-static void secure_boot_cmd(char *cmd)
-{
-	cmd_tbl_t *cmdtp;
-	int rc;
-
-	if (!cmd) {
-		printf("## Error: Secure boot command not specified\n");
-		goto err;
-	}
-
-	/* Disable Ctrl-C just in case some command is used that checks it. */
-	disable_ctrlc(1);
-
-	/* Find the command directly. */
-	cmdtp = find_cmd(cmd);
-	if (!cmdtp) {
-		printf("## Error: \"%s\" not defined\n", cmd);
-		goto err;
-	}
-
-	/* Run the command, forcing no flags and faking argc and argv. */
-	rc = (cmdtp->cmd)(cmdtp, 0, 1, &cmd);
-
-	/* Shouldn't ever return from boot command. */
-	printf("## Error: \"%s\" returned (code %d)\n", cmd, rc);
-
-err:
-	/*
-	 * Not a whole lot to do here.  Rebooting won't help much, since we'll
-	 * just end up right back here.  Just loop.
-	 */
-	hang();
-}
-
 static void process_fdt_options(const void *blob)
 {
+#if defined(CONFIG_OF_CONTROL)
 	ulong addr;
 
 	/* Add an env variable to point to a kernel payload, if available */
@@ -267,14 +222,11 @@ static void process_fdt_options(const void *blob)
 	addr = fdtdec_get_config_int(gd->fdt_blob, "rootdisk-offset", 0);
 	if (addr)
 		setenv_addr("rootaddr", (void *)(CONFIG_SYS_TEXT_BASE + addr));
-}
 #endif /* CONFIG_OF_CONTROL */
+}
 
-void bootdelay_process(void)
+const char *bootdelay_process(void)
 {
-#ifdef CONFIG_OF_CONTROL
-	char *env;
-#endif
 	char *s;
 	int bootdelay;
 #ifdef CONFIG_BOOTCOUNT_LIMIT
@@ -318,27 +270,18 @@ void bootdelay_process(void)
 	} else
 #endif /* CONFIG_BOOTCOUNT_LIMIT */
 		s = getenv("bootcmd");
-#ifdef CONFIG_OF_CONTROL
-	/* Allow the fdt to override the boot command */
-	env = fdtdec_get_config_string(gd->fdt_blob, "bootcmd");
-	if (env)
-		s = env;
 
 	process_fdt_options(gd->fdt_blob);
+	stored_bootdelay = bootdelay;
 
-	/*
-	 * If the bootsecure option was chosen, use secure_boot_cmd().
-	 * Always use 'env' in this case, since bootsecure requres that the
-	 * bootcmd was specified in the FDT too.
-	 */
-	if (fdtdec_get_config_int(gd->fdt_blob, "bootsecure", 0))
-		secure_boot_cmd(env);
-
-#endif /* CONFIG_OF_CONTROL */
+	return s;
+}
 
+void autoboot_command(const char *s)
+{
 	debug("### main_loop: bootcmd=\"%s\"\n", s ? s : "<UNDEFINED>");
 
-	if (bootdelay != -1 && s && !abortboot(bootdelay)) {
+	if (stored_bootdelay != -1 && s && !abortboot(stored_bootdelay)) {
 #if defined(CONFIG_AUTOBOOT_KEYED) && !defined(CONFIG_AUTOBOOT_KEYED_CTRLC)
 		int prev = disable_ctrlc(1);	/* disable Control C checking */
 #endif

common/cli.c

@@ -12,8 +12,11 @@
 #include <common.h>
 #include <cli.h>
 #include <cli_hush.h>
+#include <fdtdec.h>
 #include <malloc.h>
 
+DECLARE_GLOBAL_DATA_PTR;
+
 /*
  * Run a command using the selected parser.
  *
@@ -105,6 +108,69 @@ int do_run(cmd_tbl_t *cmdtp, int flag, int argc, char * const argv[])
 }
 #endif
 
+#ifdef CONFIG_OF_CONTROL
+bool cli_process_fdt(const char **cmdp)
+{
+	/* Allow the fdt to override the boot command */
+	char *env = fdtdec_get_config_string(gd->fdt_blob, "bootcmd");
+	if (env)
+		*cmdp = env;
+	/*
+	 * If the bootsecure option was chosen, use secure_boot_cmd().
+	 * Always use 'env' in this case, since bootsecure requres that the
+	 * bootcmd was specified in the FDT too.
+	 */
+	return fdtdec_get_config_int(gd->fdt_blob, "bootsecure", 0) != 0;
+}
+
+/*
+ * Runs the given boot command securely.  Specifically:
+ * - Doesn't run the command with the shell (run_command or parse_string_outer),
+ *   since that's a lot of code surface that an attacker might exploit.
+ *   Because of this, we don't do any argument parsing--the secure boot command
+ *   has to be a full-fledged u-boot command.
+ * - Doesn't check for keypresses before booting, since that could be a
+ *   security hole; also disables Ctrl-C.
+ * - Doesn't allow the command to return.
+ *
+ * Upon any failures, this function will drop into an infinite loop after
+ * printing the error message to console.
+ */
+void cli_secure_boot_cmd(const char *cmd)
+{
+	cmd_tbl_t *cmdtp;
+	int rc;
+
+	if (!cmd) {
+		printf("## Error: Secure boot command not specified\n");
+		goto err;
+	}
+
+	/* Disable Ctrl-C just in case some command is used that checks it. */
+	disable_ctrlc(1);
+
+	/* Find the command directly. */
+	cmdtp = find_cmd(cmd);
+	if (!cmdtp) {
+		printf("## Error: \"%s\" not defined\n", cmd);
+		goto err;
+	}
+
+	/* Run the command, forcing no flags and faking argc and argv. */
+	rc = (cmdtp->cmd)(cmdtp, 0, 1, (char **)&cmd);
+
+	/* Shouldn't ever return from boot command. */
+	printf("## Error: \"%s\" returned (code %d)\n", cmd, rc);
+
+err:
+	/*
+	 * Not a whole lot to do here.  Rebooting won't help much, since we'll
+	 * just end up right back here.  Just loop.
+	 */
+	hang();
+}
+#endif /* CONFIG_OF_CONTROL */
+
 void cli_loop(void)
 {
 #ifdef CONFIG_SYS_HUSH_PARSER

common/main.c

@@ -55,8 +55,11 @@ static void run_preboot_environment_command(void)
 #endif /* CONFIG_PREBOOT */
 }
 
+/* We come here after U-Boot is initialised and ready to process commands */
 void main_loop(void)
 {
+	const char *s;
+
 	bootstage_mark_name(BOOTSTAGE_ID_MAIN_LOOP, "main_loop");
 
 #ifndef CONFIG_SYS_GENERIC_BOARD
@@ -78,10 +81,11 @@ void main_loop(void)
 	update_tftp(0UL);
 #endif /* CONFIG_UPDATE_TFTP */
 
-	bootdelay_process();
-	/*
-	 * Main Loop for Monitor Command Processing
-	 */
+	s = bootdelay_process();
+	if (cli_process_fdt(&s))
+		cli_secure_boot_cmd(s);
+
+	autoboot_command(s);
 
 	cli_loop();
 }

include/autoboot.h

@@ -13,9 +13,33 @@
 #define __AUTOBOOT_H
 
 #ifdef CONFIG_BOOTDELAY
-void bootdelay_process(void);
+/**
+ * bootdelay_process() - process the bootd delay
+ *
+ * Process the boot delay, boot limit, then get the value of either
+ * bootcmd, failbootcmd or altbootcmd depending on the current state.
+ * Return this command so it can be executed.
+ *
+ * @return command to executed
+ */
+const char *bootdelay_process(void);
+
+/**
+ * autoboot_command() - run the autoboot command
+ *
+ * If enabled, run the autoboot command returned from bootdelay_process().
+ * Also do the CONFIG_MENUKEY processing if enabled.
+ *
+ * @cmd: Command to run
+ */
+void autoboot_command(const char *cmd);
 #else
-static inline void bootdelay_process(void)
+static inline const char *bootdelay_process(void)
+{
+	return NULL;
+}
+
+static inline void autoboot_command(const char *s)
 {
 }
 #endif

include/cli.h

@@ -100,6 +100,39 @@ int cli_readline_into_buffer(const char *const prompt, char *buffer,
  */
 int cli_simple_parse_line(char *line, char *argv[]);
 
+#ifdef CONFIG_OF_CONTROL
+/**
+ * cli_process_fdt() - process the boot command from the FDT
+ *
+ * If bootcmmd is defined in the /config node of the FDT, we use that
+ * as the boot command. Further, if bootsecure is set to 1 (in the same
+ * node) then we return true, indicating that the command should be executed
+ * as securely as possible, avoiding the CLI parser.
+ *
+ * @cmdp:	On entry, the command that will be executed if the FDT does
+ *		not have a command. Returns the command to execute after
+ *		checking the FDT.
+ * @return true to execute securely, else false
+ */
+bool cli_process_fdt(const char **cmdp);
+
+/** cli_secure_boot_cmd() - execute a command as securely as possible
+ *
+ * This avoids using the parser, thus executing the command with the
+ * smallest amount of code. Parameters are not supported.
+ */
+void cli_secure_boot_cmd(const char *cmd);
+#else
+static inline bool cli_process_fdt(const char **cmdp)
+{
+	return false;
+}
+
+static inline void cli_secure_boot_cmd(const char *cmd)
+{
+}
+#endif /* CONFIG_OF_CONTROL */
+
 /**
  * Go into the command loop
  *