[ImageBuilder] uboot-script-gen: use size from arm32 zImage header

[Michal Orzel <michal.orzel@xxxxxxx>]

Take an example from commit 8bf401c99035 ("uboot-script-gen: use size from
arm64 Image header") and add support for calculating the effective image
size from arm32 zImage header.

Introduce get_image_size() function and use it to to probe the supported
header magic values and to retrieve the effective image size. Use this
value in add_size(), whenever it's bigger than the one obtained using
'stat -L'.

Signed-off-by: Michal Orzel <michal.orzel@xxxxxxx>
---
This patch together with 'bootz' support will allow us to enable testing Xen
on arm{32,64} in gitlab CI with UBSAN enabled.
---
 scripts/uboot-script-gen | 38 ++++++++++++++++++++++++++++----------
 1 file changed, 28 insertions(+), 10 deletions(-)

diff --git a/scripts/uboot-script-gen b/scripts/uboot-script-gen
index 9e3d86e4743a..078a667c61ab 100755
--- a/scripts/uboot-script-gen
+++ b/scripts/uboot-script-gen
@@ -431,23 +431,41 @@ function device_tree_editing()
     fi
 }
 
-function add_size()
+# Read effective image size from a header, which may be larger than the 
filesize
+# due to noload sections, e.g. bss.
+function get_image_size()
 {
-    local filename=$1
-    local size=`stat -L --printf="%s" $filename`
+    local image=$1
+    local effective_size=0
     # Read arm64 header magic 
(https://www.kernel.org/doc/Documentation/arm64/booting.txt)
-    local arm64_header_magic=$(od -j 56 -N 4 -t x4 ${filename} | awk 'NR==1 
{print $2}')
+    local arm64_header_magic=$(od -j 56 -N 4 -t x4 ${image} | awk 'NR==1 
{print $2}')
+    # Read arm32 header magic 
(http://www.simtec.co.uk/products/SWLINUX/files/booting_article.html)
+    local arm32_header_magic=$(od -j 36 -N 4 -t x4 ${image} | awk 'NR==1 
{print $2}')
 
     # Check for valid arm64 header magic value 0x644d5241
     if [ "${arm64_header_magic}" = "644d5241" ]
     then
-        # Read effective size, which may be larger than the filesize due to 
noload sections, e.g. bss
-        local arm64_header_size=$(od -j 16 -N 8 -t u8 ${filename} | awk 'NR==1 
{print $2}')
+        effective_size=$(od -j 16 -N 8 -t u8 ${image} | awk 'NR==1 {print $2}')
+    # Check for valid arm32 header magic value 0x016f2818
+    elif [ "${arm32_header_magic}" = "016f2818" ]
+    then
+        local start=$(od -j 40 -N 4 -t u4 ${image} | awk 'NR==1 {print $2}')
+        local end=$(od -j 44 -N 4 -t u4 ${image} | awk 'NR==1 {print $2}')
+        effective_size=$(( end - start ))
+    fi
 
-        if [ "${arm64_header_size}" -gt "${size}" ]
-        then
-            size=${arm64_header_size}
-        fi
+    printf "%u" $effective_size
+}
+
+function add_size()
+{
+    local filename=$1
+    local size=`stat -L --printf="%s" $filename`
+    local image_size=`get_image_size $filename`
+
+    if [ "${image_size}" -gt "${size}" ]
+    then
+        size=${image_size}
     fi
 
     memaddr=$(( $memaddr + $size + $offset - 1))
-- 
2.25.1