bcm4908: support "rootfs_data" on U-Boot devices

1. Create "rootfs_data" dynamicaly

U-Boot firmware images can contain only 2 UBI volumes: bootfs (container
with U-Boot + kernel + DTBs) and rootfs (e.g. squashfs). There is no way
to include "rootfs_data" UBI volume or make firmware file tell U-Boot to
create one.

For that reason "rootfs_data" needs to be created dynamically. Use
preinit script to handle that. Fire it right before "mount_root" one.

2. Relate "rootfs_data" to flashed firmware

As already explained flashing new firmware with U-Boot will do nothing
to the "rootfs_data". It could result in new firmware reusing old
"rootfs_data" overlay UBI volume and its file. Users expect a clean
state after flashing firmware (even if flashing the same one).

Solve that by reading flash counter of running firmware and storing it
in "rootfs_data" UBI volume. Every mismatch will result in wiping old
data.

Signed-off-by: Rafał Miłecki <rafal@milecki.pl>

diff --git a/target/linux/bcm4908/base-files/lib/functions/bcm4908.sh b/target/linux/bcm4908/base-files/lib/functions/bcm4908.sh
new file mode 100644 (file)
index 0000000..aea31e7
--- /dev/null
+++ b/target/linux/bcm4908/base-files/lib/functions/bcm4908.sh
@@ -0,0 +1,73 @@
+# SPDX-License-Identifier: GPL-2.0-or-later OR BSD-2-Clause
+
+FS_STATE_READY=2
+
+# $(1): file to read from
+# $(2): offset in bytes
+get_hex_u32_le() {
+       dd if="$1" skip=$2 bs=1 count=4 2>/dev/null | hexdump -v -e '1/4 "%02x"'
+}
+
+# Setup /tmp/env.config to provide "metadata" UBI volume access
+#
+# It can be used with "fw_printenv -c /tmp/env.config"
+bcm4908_pkgtb_setup_env_config() {
+       local size=$((0x$(get_hex_u32_le /dev/ubi0_1 4)))
+
+       dd if=/dev/ubi0_1 of=/tmp/env.head count=8 iflag=count_bytes
+       dd if=/dev/ubi0_1 of=/tmp/env.body skip=8 iflag=skip_bytes
+       printf "%s\t0x%x\t0x%x\t0x%x" "/tmp/env.body" 0x0 $size $size > /tmp/env.config
+}
+
+bcm4908_committed_image_seq() {
+       bcm4908_pkgtb_setup_env_config
+
+       commited="$(fw_printenv -n -c /tmp/env.config COMMITTED)"
+       [ -n "$commited" ] && {
+               seq=$(fw_printenv -n -c /tmp/env.config SEQ | cut -d ',' -f $commited)
+               [ -n "$seq" ] && {
+                       echo $seq
+                       return
+               }
+       }
+
+       echo "Failed to read COMMITED and SEQ from metadata1" >&2
+}
+
+# Make sure "rootfs_data" UBI volume matches currently flashed image
+#
+# On mismatch "rootfs_data" will be wiped and assigned
+#
+# $1: UBI volume of "rootfs_data" (e.g. ubi0_123)
+bcm4908_verify_rootfs_data() {
+       local ubivol="$1"
+       local dir=/tmp/rootfs_data
+       local seq="$(bcm4908_committed_image_seq)"
+
+       [ -z "$seq" ] && return
+
+       mkdir $dir
+       if ! mount -t ubifs /dev/$ubivol $dir; then
+               echo "Failed to mount $ubivol UBI volume" >&2
+               rmdir $dir
+               return
+       fi
+
+       # Wipe rootfs_data if it doesn't belong to us
+       [ "$(readlink $dir/.openwrt-image-seq)" != "$seq" ] && {
+               echo "Removing \"rootfs_data\" content"
+               rm -rf $dir/..?* $dir/.[!.]* $dir/*
+       }
+
+       # If rootfs_data is clean (or was just wiped) claim it
+       [ -z "$(ls -A $dir)" ] && {
+               echo "Assigning \"rootfs_data\" to the current firmware"
+               # Claim this "rootfs_data"
+               ln -s $seq $dir/.openwrt-image-seq
+               # Mark it ready to avoid "mount_root" wiping it again
+               ln -s $FS_STATE_READY $dir/.fs_state
+       }
+
+       umount $dir
+       rmdir $dir
+}

diff --git a/target/linux/bcm4908/base-files/lib/preinit/75_rootfs_prepare b/target/linux/bcm4908/base-files/lib/preinit/75_rootfs_prepare
new file mode 100644 (file)
index 0000000..07fa218
--- /dev/null
+++ b/target/linux/bcm4908/base-files/lib/preinit/75_rootfs_prepare
@@ -0,0 +1,35 @@
+# SPDX-License-Identifier: GPL-2.0-or-later OR BSD-2-Clause
+
+. /lib/functions/bcm4908.sh
+
+rootfs_create() {
+       local blocks
+
+       blocks=$(cat /sys/class/ubi/ubi0/avail_eraseblocks)
+       [ -z "$blocks" ] && {
+               echo "Failed to read amount of available erase blocks" >&2
+               return
+       }
+
+       # Use 80% of remaining flash size for "rootfs_data"
+       ubimkvol /dev/ubi0 -n 20 -N rootfs_data --lebs $((blocks / 100 * 80))
+       mknod -m 0600 /dev/ubi0_20 c 252 21
+
+       bcm4908_verify_rootfs_data ubi0_20
+}
+
+rootfs_prepare() {
+       # Do nothing on CFE devices
+       ubinfo /dev/ubi0 -N metadata1 > /dev/null 2>&1 || exit 0
+
+       # Find UBI volume device (e.g. ubi0_123)
+       local ubivol="$(grep rootfs_data /sys/devices/virtual/ubi/ubi*/ubi*/name | sed -n 's/.*\(ubi\d*_\d*\).*/\1/p')"
+       if [ -n "$ubivol" ]; then
+               bcm4908_verify_rootfs_data $ubivol
+       else
+               echo "Creating \"rootfs_data\" UBI volume"
+               rootfs_create
+       fi
+}
+
+boot_hook_add preinit_main rootfs_prepare

diff --git a/target/linux/bcm4908/base-files/lib/upgrade/platform.sh b/target/linux/bcm4908/base-files/lib/upgrade/platform.sh
index 1b94801fb0f747ac2fd2cd4d7c01d0af5f121108..09743318013978b96995eab32e250db5e599b8dd 100644 (file)
--- a/target/linux/bcm4908/base-files/lib/upgrade/platform.sh
+++ b/target/linux/bcm4908/base-files/lib/upgrade/platform.sh
@@ -1,6 +1,8 @@
 # SPDX-License-Identifier: GPL-2.0 OR BSD-2-Clause
 
-RAMFS_COPY_BIN="bcm4908img expr grep fdtget fw_printenv fw_setenv tr"
+. /lib/functions/bcm4908.sh
+
+RAMFS_COPY_BIN="bcm4908img expr grep ln fdtget fw_printenv fw_setenv readlink tr"
 
 PART_NAME=firmware
 
@@ -134,17 +136,7 @@ platform_pkgtb_get_image() {
        }
 }
 
-platform_pkgtb_setup_env_config() {
-       local size=$((0x$(get_hex_u32_le /dev/ubi0_1 4)))
-
-       dd if=/dev/ubi0_1 of=/tmp/env.head count=8 iflag=count_bytes
-       dd if=/dev/ubi0_1 of=/tmp/env.body skip=8 iflag=skip_bytes
-       printf "%s\t0x%x\t0x%x\t0x%x" "/tmp/env.body" 0x0 $size $size > /tmp/env.config
-}
-
 platform_pkgtb_get_upgrade_index() {
-       platform_pkgtb_setup_env_config
-
        case "$(fw_printenv -l /tmp -n -c /tmp/env.config COMMITTED)" in
                1) echo 2;;
                2) echo 1;;
@@ -160,8 +152,6 @@ platform_pkgtb_commit() {
        local seq2
        local tmp
 
-       platform_pkgtb_setup_env_config
-
        # Read current values
        for valid in $(fw_printenv -l /tmp -n -c /tmp/env.config VALID | tr ',' ' '); do
                case "$valid" in
@@ -272,11 +262,20 @@ platform_check_image() {
 # upgrade
 #
 
+platform_pkgtb_clean_rootfs_data() {
+       local ubidev=$(nand_find_ubi $CI_UBIPART)
+       local ubivol="$(nand_find_volume $ubidev rootfs_data)"
+
+       bcm4908_verify_rootfs_data "$ubivol"
+}
+
 platform_do_upgrade_pkgtb() {
        local cmd="${2:-cat}"
        local size
        local idx bootfs_id rootfs_id
 
+       bcm4908_pkgtb_setup_env_config
+
        idx=$(platform_pkgtb_get_upgrade_index)
        case "$idx" in
                1) bootfs_id=3; rootfs_id=4;;
@@ -295,6 +294,8 @@ platform_do_upgrade_pkgtb() {
 
        platform_pkgtb_commit $idx
 
+       CI_UBIPART="image"
+       platform_pkgtb_clean_rootfs_data
        nand_do_upgrade_success
 }