make_dev_ssd: Support non-512B block size

BUG=b:114610466
BRANCH=none
TEST=(1)Test cheza, whose storage has a block size of 4k:
$ make_dev_ssd.sh --remove_rootfs_verification --partitions 2
$ make_dev_ssd.sh --partitions 2 --save_config /tmp/foo_config
$ echo "console=ttyMSM0,115200n8" >> /tmp/foo_config.2
$ make_dev_ssd.sh --partitions 2 --set_config /tmp/foo_config
Messages show kernel is successfully re-signed.
Reboot and then see kernel log printed.
Also, rootfs is modifiable.
(2)Do a similar test on scarlet, whose storage has a block size of 512B.
See the same result.

Change-Id: Ic5d7714e4f608c477f935d244cd5ad62eb38815a
Signed-off-by: Philip Chen <philipchen@google.com>
Reviewed-on: https://chromium-review.googlesource.com/1240934
Commit-Ready: ChromeOS CL Exonerator Bot <chromiumos-cl-exonerator@appspot.gserviceaccount.com>
Tested-by: Philip Chen <philipchen@chromium.org>
Reviewed-by: Hung-Te Lin <hungte@chromium.org>
Reviewed-by: Evan Green <evgreen@chromium.org>
Reviewed-by: Mike Frysinger <vapier@chromium.org>

2 files changed, 22 insertions, 7 deletions

diff --git a/scripts/image_signing/common_minimal.sh b/scripts/image_signing/common_minimal.sh
index c57fc90d..8166d698 100644
--- a/scripts/image_signing/common_minimal.sh
+++ b/scripts/image_signing/common_minimal.sh
@@ -137,6 +137,20 @@ make_partition_dev() {
   fi
 }
 
+# Find the block size of a device in bytes
+# Args: DEVICE (e.g. /dev/sda)
+# Return: block size in bytes
+blocksize() {
+  local output=''
+  local path="$1"
+  if [ -b "${path}" ]; then
+    local dev="${path##*/}"
+    local sys="/sys/block/${dev}/queue/logical_block_size"
+    output="$(cat "${sys}" 2>/dev/null)"
+  fi
+  echo "${output:-512}"
+}
+
 # Read GPT table to find the starting location of a specific partition.
 # Args: DEVICE PARTNUM
 # Returns: offset (in sectors) of partition PARTNUM
@@ -186,7 +200,8 @@ _mount_image_partition_retry() {
   local partnum=$2
   local mount_dir=$3
   local ro=$4
-  local offset=$(( $(partoffset "${image}" "${partnum}") * 512 ))
+  local bs="$(blocksize "${image}")"
+  local offset=$(( $(partoffset "${image}" "${partnum}") * bs ))
   local out try
 
   set -- sudo LC_ALL=C mount -o loop,offset=${offset},${ro} \
@@ -225,7 +240,8 @@ _mount_image_partition() {
   local partnum=$2
   local mount_dir=$3
   local ro=$4
-  local offset=$(( $(partoffset "${image}" "${partnum}") * 512 ))
+  local bs="$(blocksize "${image}")"
+  local offset=$(( $(partoffset "${image}" "${partnum}") * bs ))
 
   if [ "$ro" != "ro" ]; then
     # Forcibly call enable_rw_mount.  It should fail on unsupported
diff --git a/scripts/image_signing/make_dev_ssd.sh b/scripts/image_signing/make_dev_ssd.sh
index b08ca48c..5871a190 100755
--- a/scripts/image_signing/make_dev_ssd.sh
+++ b/scripts/image_signing/make_dev_ssd.sh
@@ -144,13 +144,12 @@ find_valid_kernel_partitions() {
 
 # Resigns a kernel on SSD or image.
 resign_ssd_kernel() {
-  # bs=512 is the fixed block size for dd and cgpt
-  local bs=512
   local ssd_device="$1"
+  local bs="$(blocksize "${ssd_device}")"
 
   # reasonable size for current kernel partition
-  local min_kernel_size=16000
-  local max_kernel_size=65536
+  local min_kernel_size=$((8000 * 1024 / bs))
+  local max_kernel_size=$((32768 * 1024 / bs))
   local resigned_kernels=0
 
   for kernel_index in $FLAGS_partitions; do
@@ -302,7 +301,7 @@ resign_ssd_kernel() {
     # (3) change kernel config to rw
     if [ ${FLAGS_remove_rootfs_verification} = $FLAGS_TRUE ]; then
       local root_offset_sector=$(partoffset "$ssd_device" $rootfs_index)
-      local root_offset_bytes=$((root_offset_sector * 512))
+      local root_offset_bytes=$((root_offset_sector * bs))
       if ! is_ext2 "$ssd_device" "$root_offset_bytes"; then
         debug_msg "Non-ext2 partition: $ssd_device$rootfs_index, skip."
       elif ! rw_mount_disabled "$ssd_device" "$root_offset_bytes"; then