common/android_bootloader.c

/*
 * Copyright (C) 2016 The Android Open Source Project
 *
 * SPDX-License-Identifier: BSD-2-Clause
 */

#include <android_bootloader.h>
#include <android_bootloader_message.h>

#include <cli.h>
#include <common.h>
#include <malloc.h>

#define ANDROID_PARTITION_BOOT "boot"
#define ANDROID_PARTITION_SYSTEM "system"

#define ANDROID_ARG_SLOT_SUFFIX "androidboot.slot_suffix="
#define ANDROID_ARG_ROOT "root="

static int android_bootloader_message_load(
	struct blk_desc *dev_desc,
	const disk_partition_t *part_info,
	struct android_bootloader_message *message)
{
	ulong message_blocks = sizeof(struct android_bootloader_message) /
	    part_info->blksz;
	if (message_blocks > part_info->size) {
		printf("misc partition too small.\n");
		return -1;
	}

	if (blk_dread(dev_desc, part_info->start, message_blocks, message) !=
	    message_blocks) {
		printf("Could not read from misc partition\n");
		return -1;
	}
	debug("ANDROID: Loaded BCB, %lu blocks.\n", message_blocks);
	return 0;
}

static int android_bootloader_message_write(
	struct blk_desc *dev_desc,
	const disk_partition_t *part_info,
	struct android_bootloader_message *message)
{
	ulong message_blocks = sizeof(struct android_bootloader_message) /
	    part_info->blksz;
	if (message_blocks > part_info->size) {
		printf("misc partition too small.\n");
		return -1;
	}

	if (blk_dwrite(dev_desc, part_info->start, message_blocks, message) !=
	    message_blocks) {
		printf("Could not write to misc partition\n");
		return -1;
	}
	debug("ANDROID: Wrote new BCB, %lu blocks.\n", message_blocks);
	return 0;
}

static enum android_boot_mode android_bootloader_load_and_clear_mode(
	struct blk_desc *dev_desc,
	const disk_partition_t *misc_part_info)
{
	struct android_bootloader_message bcb;

#ifdef CONFIG_FASTBOOT
	char *bootloader_str;

	/* Check for message from bootloader stored in RAM from a previous boot.
	 */
	bootloader_str = (char *)CONFIG_FASTBOOT_BUF_ADDR;
	if (!strcmp("reboot-bootloader", bootloader_str)) {
		bootloader_str[0] = '\0';
		return ANDROID_BOOT_MODE_BOOTLOADER;
	}
#endif

	/* Check and update the BCB message if needed. */
	if (android_bootloader_message_load(dev_desc, misc_part_info, &bcb) <
	    0) {
		printf("WARNING: Unable to load the BCB.\n");
		return ANDROID_BOOT_MODE_NORMAL;
	}

	if (!strcmp("bootonce-bootloader", bcb.command)) {
		/* Erase the message in the BCB since this value should be used
		 * only once.
		 */
		memset(bcb.command, 0, sizeof(bcb.command));
		android_bootloader_message_write(dev_desc, misc_part_info,
						 &bcb);
		return ANDROID_BOOT_MODE_BOOTLOADER;
	}

	if (!strcmp("boot-recovery", bcb.command))
		return ANDROID_BOOT_MODE_RECOVERY;

	return ANDROID_BOOT_MODE_NORMAL;
}

/**
 * Return the reboot reason string for the passed boot mode.
 *
 * @param mode	The Android Boot mode.
 * @return a pointer to the reboot reason string for mode.
 */
static const char *android_boot_mode_str(enum android_boot_mode mode)
{
	switch (mode) {
	case ANDROID_BOOT_MODE_NORMAL:
		return "(none)";
	case ANDROID_BOOT_MODE_RECOVERY:
		return "recovery";
	case ANDROID_BOOT_MODE_BOOTLOADER:
		return "bootloader";
	}
	return NULL;
}

static int android_part_get_info_by_name_suffix(struct blk_desc *dev_desc,
						const char *base_name,
						const char *slot_suffix,
						disk_partition_t *part_info)
{
	char *part_name;
	int part_num;
	size_t part_name_len;

	part_name_len = strlen(base_name) + 1;
	if (slot_suffix)
		part_name_len += strlen(slot_suffix);
	part_name = malloc(part_name_len);
	if (!part_name)
		return -1;
	strcpy(part_name, base_name);
	if (slot_suffix)
		strcat(part_name, slot_suffix);

	part_num = part_get_info_by_name(dev_desc, part_name, part_info);
	if (part_num < 0) {
		debug("ANDROID: Could not find partition \"%s\"\n", part_name);
		part_num = -1;
	}

	free(part_name);
	return part_num;
}

static int android_bootloader_boot_bootloader(void)
{
	const char *fastboot_cmd = env_get("fastbootcmd");

	if (fastboot_cmd)
		return run_command(fastboot_cmd, CMD_FLAG_ENV);
	return -1;
}

static int android_bootloader_boot_kernel(unsigned long kernel_address)
{
	char kernel_addr_str[12];
	char *fdt_addr = env_get("fdt_addr");
	char *bootm_args[] = {
		"bootm", kernel_addr_str, kernel_addr_str, fdt_addr, NULL };

	sprintf(kernel_addr_str, "0x%lx", kernel_address);

	printf("Booting kernel at %s with fdt at %s...\n\n\n",
	       kernel_addr_str, fdt_addr);
	do_bootm(NULL, 0, 4, bootm_args);

	return -1;
}

static char *strjoin(const char **chunks, char separator)
{
	int len, joined_len = 0;
	char *ret, *current;
	const char **p;

	for (p = chunks; *p; p++)
		joined_len += strlen(*p) + 1;

	if (!joined_len) {
		ret = malloc(1);
		if (ret)
			ret[0] = '\0';
		return ret;
	}

	ret = malloc(joined_len);
	current = ret;
	if (!ret)
		return ret;

	for (p = chunks; *p; p++) {
		len = strlen(*p);
		memcpy(current, *p, len);
		current += len;
		*current = separator;
		current++;
	}
	/* Replace the last separator by a \0. */
	current[-1] = '\0';
	return ret;
}

/** android_assemble_cmdline - Assemble the command line to pass to the kernel
 * @return a newly allocated string
 */
static char *android_assemble_cmdline(const char *slot_suffix,
				      const char *extra_args)
{
	const char *cmdline_chunks[16];
	const char **current_chunk = cmdline_chunks;
	char *env_cmdline, *cmdline, *rootdev_input;
	char *allocated_suffix = NULL;
	char *allocated_rootdev = NULL;
	unsigned long rootdev_len;

	env_cmdline = env_get("bootargs");
	if (env_cmdline)
		*(current_chunk++) = env_cmdline;

	/* The |slot_suffix| needs to be passed to the kernel to know what
	 * slot to boot from.
	 */
	if (slot_suffix) {
		allocated_suffix = malloc(strlen(ANDROID_ARG_SLOT_SUFFIX) +
					  strlen(slot_suffix));
		strcpy(allocated_suffix, ANDROID_ARG_SLOT_SUFFIX);
		strcat(allocated_suffix, slot_suffix);
		*(current_chunk++) = allocated_suffix;
	}

	rootdev_input = env_get("android_rootdev");
	if (rootdev_input) {
		rootdev_len = strlen(ANDROID_ARG_ROOT) + CONFIG_SYS_CBSIZE + 1;
		allocated_rootdev = malloc(rootdev_len);
		strcpy(allocated_rootdev, ANDROID_ARG_ROOT);
		cli_simple_process_macros(rootdev_input,
					  allocated_rootdev +
					  strlen(ANDROID_ARG_ROOT));
		/* Make sure that the string is null-terminated since the
		 * previous could not copy to the end of the input string if it
		 * is too big.
		 */
		allocated_rootdev[rootdev_len - 1] = '\0';
		*(current_chunk++) = allocated_rootdev;
	}

	if (extra_args)
		*(current_chunk++) = extra_args;

	*(current_chunk++) = NULL;
	cmdline = strjoin(cmdline_chunks, ' ');
	free(allocated_suffix);
	free(allocated_rootdev);
	return cmdline;
}

int android_bootloader_boot_flow(struct blk_desc *dev_desc,
				 const disk_partition_t *misc_part_info,
				 const char *slot,
				 unsigned long kernel_address)
{
	enum android_boot_mode mode;
	disk_partition_t boot_part_info;
	disk_partition_t system_part_info;
	int boot_part_num, system_part_num;
	int ret;
	char *command_line;
	char slot_suffix[3];
	const char *mode_cmdline = NULL;

	/* Determine the boot mode and clear its value for the next boot if
	 * needed.
	 */
	mode = android_bootloader_load_and_clear_mode(dev_desc, misc_part_info);
	printf("ANDROID: reboot reason: \"%s\"\n", android_boot_mode_str(mode));

	switch (mode) {
	case ANDROID_BOOT_MODE_NORMAL:
		/* In normal mode, we load the kernel from "boot" but append
		 * "skip_initramfs" to the cmdline to make it ignore the
		 * recovery initramfs in the boot partition.
		 */
		mode_cmdline = "skip_initramfs";
		break;
	case ANDROID_BOOT_MODE_RECOVERY:
		/* In recovery mode we still boot the kernel from "boot" but
		 * don't skip the initramfs so it boots to recovery.
		 */
		break;
	case ANDROID_BOOT_MODE_BOOTLOADER:
		/* Bootloader mode enters fastboot. If this operation fails we
		 * simply return since we can't recover from this situation by
		 * switching to another slot.
		 */
		return android_bootloader_boot_bootloader();
	}

	slot_suffix[0] = '\0';
	if (slot && slot[0]) {
		slot_suffix[0] = '_';
		slot_suffix[1] = slot[0];
		slot_suffix[2] = '\0';
	}

	/* Load the kernel from the desired "boot" partition. */
	boot_part_num =
	    android_part_get_info_by_name_suffix(dev_desc,
						 ANDROID_PARTITION_BOOT,
						 slot_suffix, &boot_part_info);
	if (boot_part_num < 0)
		return -1;
	debug("ANDROID: Loading kernel from \"%s\", partition %d.\n",
	      boot_part_info.name, boot_part_num);

	system_part_num =
	    android_part_get_info_by_name_suffix(dev_desc,
						 ANDROID_PARTITION_SYSTEM,
						 slot_suffix,
						 &system_part_info);
	if (system_part_num < 0)
		return -1;
	debug("ANDROID: Using system image from \"%s\", partition %d.\n",
	      system_part_info.name, system_part_num);

	ret = android_image_load(dev_desc, &boot_part_info, kernel_address,
				 -1UL);
	if (ret < 0)
		return ret;

	/* Set Android root variables. */
	env_set_ulong("android_root_devnum", dev_desc->devnum);
	env_set_ulong("android_root_partnum", system_part_num);
	env_set("android_slotsufix", slot_suffix);

	/* Assemble the command line */
	command_line = android_assemble_cmdline(slot_suffix, mode_cmdline);
	env_set("bootargs", command_line);

	debug("ANDROID: bootargs: \"%s\"\n", command_line);

	android_bootloader_boot_kernel(kernel_address);

	/* TODO: If the kernel doesn't boot mark the selected slot as bad. */
	return -1;
}