Boot control HAL based on the A/B headers.
The added bootctrl.bcb module implement the legacy interface for the
bootctrl HAL based on the Boot Control Block (BCB) and the headers
already specified in the booloader_message library.
This serves as a reference implementation of the boot_control HAL.
Bug: 32707546
Test: Tested internally that a device can use this HAL to flip slots and
recovery from a /misc wipe.
Change-Id: Ic02e5aaf4de7d0a1780eac4e8705dae20d0b3e10
diff --git a/Android.mk b/Android.mk
index 037aa16..d701013 100644
--- a/Android.mk
+++ b/Android.mk
@@ -160,6 +160,7 @@
include \
$(LOCAL_PATH)/applypatch/Android.mk \
+ $(LOCAL_PATH)/boot_control/Android.mk \
$(LOCAL_PATH)/bootloader_message/Android.mk \
$(LOCAL_PATH)/edify/Android.mk \
$(LOCAL_PATH)/minadbd/Android.mk \
diff --git a/boot_control/Android.mk b/boot_control/Android.mk
new file mode 100644
index 0000000..27e3d97
--- /dev/null
+++ b/boot_control/Android.mk
@@ -0,0 +1,34 @@
+#
+# Copyright (C) 2017 The Android Open Source Project
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+# http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+#
+
+LOCAL_PATH := $(my-dir)
+
+include $(CLEAR_VARS)
+LOCAL_MODULE := bootctrl.bcb
+LOCAL_MODULE_RELATIVE_PATH := hw
+LOCAL_SRC_FILES := boot_control.cpp
+LOCAL_CFLAGS := \
+ -D_FILE_OFFSET_BITS=64 \
+ -Werror \
+ -Wall \
+ -Wextra \
+ -Wno-unused-parameter
+LOCAL_SHARED_LIBRARIES := liblog
+LOCAL_STATIC_LIBRARIES := libbootloader_message libfs_mgr libbase
+LOCAL_POST_INSTALL_CMD := \
+ $(hide) mkdir -p $(TARGET_OUT_SHARED_LIBRARIES)/hw && \
+ ln -sf bootctrl.bcb.so $(TARGET_OUT_SHARED_LIBRARIES)/hw/bootctrl.default.so
+include $(BUILD_SHARED_LIBRARY)
diff --git a/boot_control/boot_control.cpp b/boot_control/boot_control.cpp
new file mode 100644
index 0000000..ec97b6c
--- /dev/null
+++ b/boot_control/boot_control.cpp
@@ -0,0 +1,401 @@
+/*
+ * Copyright (C) 2015 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include <endian.h>
+#include <errno.h>
+#include <fcntl.h>
+#include <string.h>
+
+#include <string>
+
+#include <android-base/file.h>
+#include <android-base/logging.h>
+#include <android-base/properties.h>
+#include <android-base/stringprintf.h>
+#include <android-base/unique_fd.h>
+#include <hardware/boot_control.h>
+#include <hardware/hardware.h>
+
+#include <bootloader_message/bootloader_message.h>
+
+struct boot_control_private_t {
+ // The base struct needs to be first in the list.
+ boot_control_module_t base;
+
+ // Whether this struct was initialized with data from the bootloader message
+ // that doesn't change until next reboot.
+ bool initialized;
+
+ // The path to the misc_device as reported in the fstab.
+ const char* misc_device;
+
+ // The number of slots present on the device.
+ unsigned int num_slots;
+
+ // The slot where we are running from.
+ unsigned int current_slot;
+};
+
+namespace {
+
+// The number of boot attempts that should be made from a new slot before
+// rolling back to the previous slot.
+constexpr unsigned int kDefaultBootAttempts = 7;
+static_assert(kDefaultBootAttempts < 8, "tries_remaining field only has 3 bits");
+
+constexpr unsigned int kMaxNumSlots =
+ sizeof(bootloader_control::slot_info) / sizeof(bootloader_control::slot_info[0]);
+constexpr const char* kSlotSuffixes[kMaxNumSlots] = { "_a", "_b", "_c", "_d" };
+constexpr off_t kBootloaderControlOffset = offsetof(bootloader_message_ab, slot_suffix);
+
+static uint32_t CRC32(const uint8_t* buf, size_t size) {
+ static uint32_t crc_table[256];
+
+ // Compute the CRC-32 table only once.
+ if (!crc_table[1]) {
+ for (uint32_t i = 0; i < 256; ++i) {
+ uint32_t crc = i;
+ for (uint32_t j = 0; j < 8; ++j) {
+ uint32_t mask = -(crc & 1);
+ crc = (crc >> 1) ^ (0xEDB88320 & mask);
+ }
+ crc_table[i] = crc;
+ }
+ }
+
+ uint32_t ret = -1;
+ for (size_t i = 0; i < size; ++i) {
+ ret = (ret >> 8) ^ crc_table[(ret ^ buf[i]) & 0xFF];
+ }
+
+ return ~ret;
+}
+
+// Return the little-endian representation of the CRC-32 of the first fields
+// in |boot_ctrl| up to the crc32_le field.
+uint32_t BootloaderControlLECRC(const bootloader_control* boot_ctrl) {
+ return htole32(
+ CRC32(reinterpret_cast<const uint8_t*>(boot_ctrl), offsetof(bootloader_control, crc32_le)));
+}
+
+bool LoadBootloaderControl(const char* misc_device, bootloader_control* buffer) {
+ android::base::unique_fd fd(open(misc_device, O_RDONLY));
+ if (fd.get() == -1) {
+ PLOG(ERROR) << "failed to open " << misc_device;
+ return false;
+ }
+ if (lseek(fd, kBootloaderControlOffset, SEEK_SET) != kBootloaderControlOffset) {
+ PLOG(ERROR) << "failed to lseek " << misc_device;
+ return false;
+ }
+ if (!android::base::ReadFully(fd.get(), buffer, sizeof(bootloader_control))) {
+ PLOG(ERROR) << "failed to read " << misc_device;
+ return false;
+ }
+ return true;
+}
+
+bool UpdateAndSaveBootloaderControl(const char* misc_device, bootloader_control* buffer) {
+ buffer->crc32_le = BootloaderControlLECRC(buffer);
+ android::base::unique_fd fd(open(misc_device, O_WRONLY | O_SYNC));
+ if (fd.get() == -1) {
+ PLOG(ERROR) << "failed to open " << misc_device;
+ return false;
+ }
+ if (lseek(fd.get(), kBootloaderControlOffset, SEEK_SET) != kBootloaderControlOffset) {
+ PLOG(ERROR) << "failed to lseek " << misc_device;
+ return false;
+ }
+ if (!android::base::WriteFully(fd.get(), buffer, sizeof(bootloader_control))) {
+ PLOG(ERROR) << "failed to write " << misc_device;
+ return false;
+ }
+ return true;
+}
+
+void InitDefaultBootloaderControl(const boot_control_private_t* module,
+ bootloader_control* boot_ctrl) {
+ memset(boot_ctrl, 0, sizeof(*boot_ctrl));
+
+ if (module->current_slot < kMaxNumSlots) {
+ strlcpy(boot_ctrl->slot_suffix, kSlotSuffixes[module->current_slot],
+ sizeof(boot_ctrl->slot_suffix));
+ }
+ boot_ctrl->magic = BOOT_CTRL_MAGIC;
+ boot_ctrl->version = BOOT_CTRL_VERSION;
+
+ // Figure out the number of slots by checking if the partitions exist,
+ // otherwise assume the maximum supported by the header.
+ boot_ctrl->nb_slot = kMaxNumSlots;
+ std::string base_path = module->misc_device;
+ size_t last_path_sep = base_path.rfind('/');
+ if (last_path_sep != std::string::npos) {
+ // We test the existence of the "boot" partition on each possible slot,
+ // which is a partition required by Android Bootloader Requirements.
+ base_path = base_path.substr(0, last_path_sep + 1) + "boot";
+ int last_existing_slot = -1;
+ int first_missing_slot = -1;
+ for (unsigned int slot = 0; slot < kMaxNumSlots; ++slot) {
+ std::string partition_path = base_path + kSlotSuffixes[slot];
+ struct stat part_stat;
+ int err = stat(partition_path.c_str(), &part_stat);
+ if (!err) {
+ last_existing_slot = slot;
+ LOG(INFO) << "Found slot: " << kSlotSuffixes[slot];
+ } else if (err < 0 && errno == ENOENT && first_missing_slot == -1) {
+ first_missing_slot = slot;
+ }
+ }
+ // We only declare that we found the actual number of slots if we found all
+ // the boot partitions up to the number of slots, and no boot partition
+ // after that. Not finding any of the boot partitions implies a problem so
+ // we just leave the number of slots in the maximum value.
+ if ((last_existing_slot != -1 && last_existing_slot + 1 == first_missing_slot) ||
+ (first_missing_slot == -1 && last_existing_slot + 1 == kMaxNumSlots)) {
+ boot_ctrl->nb_slot = last_existing_slot + 1;
+ LOG(INFO) << "Found a system with " << last_existing_slot + 1 << " slots.";
+ }
+ }
+
+ for (unsigned int slot = 0; slot < kMaxNumSlots; ++slot) {
+ slot_metadata entry = {};
+
+ if (slot < boot_ctrl->nb_slot) {
+ entry.priority = 7;
+ entry.tries_remaining = kDefaultBootAttempts;
+ entry.successful_boot = 0;
+ } else {
+ entry.priority = 0; // Unbootable
+ }
+
+ // When the boot_control stored on disk is invalid, we assume that the
+ // current slot is successful. The bootloader should repair this situation
+ // before booting and write a valid boot_control slot, so if we reach this
+ // stage it means that the misc partition was corrupted since boot.
+ if (module->current_slot == slot) {
+ entry.successful_boot = 1;
+ }
+
+ boot_ctrl->slot_info[slot] = entry;
+ }
+ boot_ctrl->recovery_tries_remaining = 0;
+
+ boot_ctrl->crc32_le = BootloaderControlLECRC(boot_ctrl);
+}
+
+// Return the index of the slot suffix passed or -1 if not a valid slot suffix.
+int SlotSuffixToIndex(const char* suffix) {
+ for (unsigned int slot = 0; slot < kMaxNumSlots; ++slot) {
+ if (!strcmp(kSlotSuffixes[slot], suffix)) return slot;
+ }
+ return -1;
+}
+
+// Initialize the boot_control_private struct with the information from
+// the bootloader_message buffer stored in |boot_ctrl|. Returns whether the
+// initialization succeeded.
+bool BootControl_lazyInitialization(boot_control_private_t* module) {
+ if (module->initialized) return true;
+
+ // Initialize the current_slot from the read-only property. If the property
+ // was not set (from either the command line or the device tree), we can later
+ // initialize it from the bootloader_control struct.
+ std::string suffix_prop = android::base::GetProperty("ro.boot.slot_suffix", "");
+ module->current_slot = SlotSuffixToIndex(suffix_prop.c_str());
+
+ std::string err;
+ std::string device = get_bootloader_message_blk_device(&err);
+ if (device.empty()) return false;
+
+ bootloader_control boot_ctrl;
+ if (!LoadBootloaderControl(device.c_str(), &boot_ctrl)) return false;
+
+ // Note that since there isn't a module unload function this memory is leaked.
+ module->misc_device = strdup(device.c_str());
+ module->initialized = true;
+
+ // Validate the loaded data, otherwise we will destroy it and re-initialize it
+ // with the current information.
+ uint32_t computed_crc32 = BootloaderControlLECRC(&boot_ctrl);
+ if (boot_ctrl.crc32_le != computed_crc32) {
+ LOG(WARNING) << "Invalid boot control found, expected CRC-32 0x" << std::hex << computed_crc32
+ << " but found 0x" << std::hex << boot_ctrl.crc32_le << ". Re-initializing.";
+ InitDefaultBootloaderControl(module, &boot_ctrl);
+ UpdateAndSaveBootloaderControl(device.c_str(), &boot_ctrl);
+ }
+
+ module->num_slots = boot_ctrl.nb_slot;
+ return true;
+}
+
+void BootControl_init(boot_control_module_t* module) {
+ BootControl_lazyInitialization(reinterpret_cast<boot_control_private_t*>(module));
+}
+
+unsigned int BootControl_getNumberSlots(boot_control_module_t* module) {
+ return reinterpret_cast<boot_control_private_t*>(module)->num_slots;
+}
+
+unsigned int BootControl_getCurrentSlot(boot_control_module_t* module) {
+ return reinterpret_cast<boot_control_private_t*>(module)->current_slot;
+}
+
+int BootControl_markBootSuccessful(boot_control_module_t* module) {
+ boot_control_private_t* const bootctrl_module = reinterpret_cast<boot_control_private_t*>(module);
+
+ bootloader_control bootctrl;
+ if (!LoadBootloaderControl(bootctrl_module->misc_device, &bootctrl)) return -1;
+
+ bootctrl.slot_info[bootctrl_module->current_slot].successful_boot = 1;
+ // tries_remaining == 0 means that the slot is not bootable anymore, make
+ // sure we mark the current slot as bootable if it succeeds in the last
+ // attempt.
+ bootctrl.slot_info[bootctrl_module->current_slot].tries_remaining = 1;
+ if (!UpdateAndSaveBootloaderControl(bootctrl_module->misc_device, &bootctrl)) return -1;
+ return 0;
+}
+
+int BootControl_setActiveBootSlot(boot_control_module_t* module, unsigned int slot) {
+ boot_control_private_t* const bootctrl_module = reinterpret_cast<boot_control_private_t*>(module);
+
+ if (slot >= kMaxNumSlots || slot >= bootctrl_module->num_slots) {
+ // Invalid slot number.
+ return -1;
+ }
+
+ bootloader_control bootctrl;
+ if (!LoadBootloaderControl(bootctrl_module->misc_device, &bootctrl)) return -1;
+
+ // Set every other slot with a lower priority than the new "active" slot.
+ const unsigned int kActivePriority = 15;
+ const unsigned int kActiveTries = 6;
+ for (unsigned int i = 0; i < bootctrl_module->num_slots; ++i) {
+ if (i != slot) {
+ if (bootctrl.slot_info[i].priority >= kActivePriority)
+ bootctrl.slot_info[i].priority = kActivePriority - 1;
+ }
+ }
+
+ // Note that setting a slot as active doesn't change the successful bit.
+ // The successful bit will only be changed by setSlotAsUnbootable().
+ bootctrl.slot_info[slot].priority = kActivePriority;
+ bootctrl.slot_info[slot].tries_remaining = kActiveTries;
+
+ // Setting the current slot as active is a way to revert the operation that
+ // set *another* slot as active at the end of an updater. This is commonly
+ // used to cancel the pending update. We should only reset the verity_corrpted
+ // bit when attempting a new slot, otherwise the verity bit on the current
+ // slot would be flip.
+ if (slot != bootctrl_module->current_slot) bootctrl.slot_info[slot].verity_corrupted = 0;
+
+ if (!UpdateAndSaveBootloaderControl(bootctrl_module->misc_device, &bootctrl)) return -1;
+ return 0;
+}
+
+int BootControl_setSlotAsUnbootable(struct boot_control_module* module, unsigned int slot) {
+ boot_control_private_t* const bootctrl_module = reinterpret_cast<boot_control_private_t*>(module);
+
+ if (slot >= kMaxNumSlots || slot >= bootctrl_module->num_slots) {
+ // Invalid slot number.
+ return -1;
+ }
+
+ bootloader_control bootctrl;
+ if (!LoadBootloaderControl(bootctrl_module->misc_device, &bootctrl)) return -1;
+
+ // The only way to mark a slot as unbootable, regardless of the priority is to
+ // set the tries_remaining to 0.
+ bootctrl.slot_info[slot].successful_boot = 0;
+ bootctrl.slot_info[slot].tries_remaining = 0;
+ if (!UpdateAndSaveBootloaderControl(bootctrl_module->misc_device, &bootctrl)) return -1;
+ return 0;
+}
+
+int BootControl_isSlotBootable(struct boot_control_module* module, unsigned int slot) {
+ boot_control_private_t* const bootctrl_module = reinterpret_cast<boot_control_private_t*>(module);
+
+ if (slot >= kMaxNumSlots || slot >= bootctrl_module->num_slots) {
+ // Invalid slot number.
+ return -1;
+ }
+
+ bootloader_control bootctrl;
+ if (!LoadBootloaderControl(bootctrl_module->misc_device, &bootctrl)) return -1;
+
+ return bootctrl.slot_info[slot].tries_remaining;
+}
+
+int BootControl_isSlotMarkedSuccessful(struct boot_control_module* module, unsigned int slot) {
+ boot_control_private_t* const bootctrl_module = reinterpret_cast<boot_control_private_t*>(module);
+
+ if (slot >= kMaxNumSlots || slot >= bootctrl_module->num_slots) {
+ // Invalid slot number.
+ return -1;
+ }
+
+ bootloader_control bootctrl;
+ if (!LoadBootloaderControl(bootctrl_module->misc_device, &bootctrl)) return -1;
+
+ return bootctrl.slot_info[slot].successful_boot && bootctrl.slot_info[slot].tries_remaining;
+}
+
+const char* BootControl_getSuffix(boot_control_module_t* module, unsigned int slot) {
+ if (slot >= kMaxNumSlots || slot >= reinterpret_cast<boot_control_private_t*>(module)->num_slots) {
+ return NULL;
+ }
+ return kSlotSuffixes[slot];
+}
+
+static int BootControl_open(const hw_module_t* module __unused, const char* id __unused,
+ hw_device_t** device __unused) {
+ /* Nothing to do currently. */
+ return 0;
+}
+
+struct hw_module_methods_t BootControl_methods = {
+ .open = BootControl_open,
+};
+
+} // namespace
+
+boot_control_private_t HAL_MODULE_INFO_SYM = {
+ .base =
+ {
+ .common =
+ {
+ .tag = HARDWARE_MODULE_TAG,
+ .module_api_version = BOOT_CONTROL_MODULE_API_VERSION_0_1,
+ .hal_api_version = HARDWARE_HAL_API_VERSION,
+ .id = BOOT_CONTROL_HARDWARE_MODULE_ID,
+ .name = "AOSP reference bootctrl HAL",
+ .author = "The Android Open Source Project",
+ .methods = &BootControl_methods,
+ },
+ .init = BootControl_init,
+ .getNumberSlots = BootControl_getNumberSlots,
+ .getCurrentSlot = BootControl_getCurrentSlot,
+ .markBootSuccessful = BootControl_markBootSuccessful,
+ .setActiveBootSlot = BootControl_setActiveBootSlot,
+ .setSlotAsUnbootable = BootControl_setSlotAsUnbootable,
+ .isSlotBootable = BootControl_isSlotBootable,
+ .getSuffix = BootControl_getSuffix,
+ .isSlotMarkedSuccessful = BootControl_isSlotMarkedSuccessful,
+ },
+ .initialized = false,
+ .misc_device = nullptr,
+ .num_slots = 0,
+ .current_slot = 0,
+};
diff --git a/bootloader_message/bootloader_message.cpp b/bootloader_message/bootloader_message.cpp
index d8086be..f91446b 100644
--- a/bootloader_message/bootloader_message.cpp
+++ b/bootloader_message/bootloader_message.cpp
@@ -117,6 +117,13 @@
return true;
}
+std::string get_bootloader_message_blk_device(std::string* err) {
+ std::string misc_blk_device = get_misc_blk_device(err);
+ if (misc_blk_device.empty()) return "";
+ if (!wait_for_device(misc_blk_device, err)) return "";
+ return misc_blk_device;
+}
+
bool read_bootloader_message_from(bootloader_message* boot, const std::string& misc_blk_device,
std::string* err) {
return read_misc_partition(boot, sizeof(*boot), misc_blk_device,
diff --git a/bootloader_message/include/bootloader_message/bootloader_message.h b/bootloader_message/include/bootloader_message/bootloader_message.h
index bc5104d..2ffbfc9 100644
--- a/bootloader_message/include/bootloader_message/bootloader_message.h
+++ b/bootloader_message/include/bootloader_message/bootloader_message.h
@@ -180,6 +180,11 @@
#include <string>
#include <vector>
+// Return the block device name for the bootloader message partition and waits
+// for the device for up to 10 seconds. In case of error returns the empty
+// string.
+std::string get_bootloader_message_blk_device(std::string* err);
+
// Read bootloader message into boot. Error message will be set in err.
bool read_bootloader_message(bootloader_message* boot, std::string* err);
