[coreboot-gerrit] New patch to review for coreboot: Exynos7: Revisit the checksum and header calculation

[Stefan Reinauer (stefan.reinauer@coreboot.org)]

Stefan Reinauer (stefan.reinauer at coreboot.org) just uploaded a new patch set to gerrit, which you can find at https://review.coreboot.org/14904

-gerrit

commit 25ee098aee3906e4be325bed887d6fa603fcda86
Author: Alim Akhtar <alim.akhtar at samsung.com>
Date:   Fri Sep 5 16:22:33 2014 +0530

    Exynos7: Revisit the checksum and header calculation
    
    Exynos7 BL1 checks the validity of BL2 by reading a 16 bytes
    long header of the bl2. BL1 calculates and compares the checksum
    of BL2 with the one mentioned in the BL2's header.
    This patch modifies header populating script to update BL2 header
    with the checksum as per BL1's requirement.
    
    BUG=None
    BRANCH=None
    TEST=Compiled and booted Coreboot over Jazz mainboard
    	with this series
    
    Change-Id: Iaf870070707f6f617bbabfc45dd9b87934b6266b
    Signed-off-by: Alim Akhtar <alim.akhtar at samsung.com>
    Signed-off-by: Vivek Gautam <gautam.vivek at samsung.com>
    Signed-off-by: Akshay Saraswat <akshay.s at samsung.com>
---
 util/exynos/variable_cksum.py | 26 +++++++++++++++++---------
 1 file changed, 17 insertions(+), 9 deletions(-)

diff --git a/util/exynos/variable_cksum.py b/util/exynos/variable_cksum.py
index 541e06d..8d7cba2 100755
--- a/util/exynos/variable_cksum.py
+++ b/util/exynos/variable_cksum.py
@@ -29,16 +29,18 @@
 This utility computes and fills Exynos ROM checksum (for BL1 or BL2).
 (Algorithm from U-Boot: tools/mkexynosspl.c)
 
-Input: IN OUT <size_in_blocks>
+Input: IN OUT <size_in_blocks> <checksum-type>
 
 Output:
 
   Checksum header added to IN and written to OUT.
-  Header: uint32_t size, checksum, reserved[2].
+  Header: uint32_t size, checksum, String "head", reserved[1].
 """
 
 import struct
 import sys
+import hashlib
+import binascii
 
 # Get the number of byte needed to make _data_ 512 byte alinged
 def alignpos(pos, alignbytes):
@@ -46,8 +48,8 @@ def alignpos(pos, alignbytes):
     return (pos + mask) & ~mask
 
 def main(argv):
-  if len(argv) < 3 or len(argv) > 4:
-    exit('usage: %s IN OUT <size_in_blocks>' % argv[0])
+  if len(argv) < 3 or len(argv) > 5:
+    exit('usage: %s IN OUT <size_in_blocks> <checksum-type>' % argv[0])
 
   in_name, out_name = argv[1:3]
   header_format = "<IIII"
@@ -63,12 +65,18 @@ def main(argv):
 	else:
 	    size = (size / block_size)
 
-    header = struct.pack(header_format,
-			 size,
-                         sum(map(ord, data)),
-                         0, 0)
-    out_file.write(header + data)
+    if "sha256" in argv:
+	hash_obj = hashlib.sha256(data)
+	hex_dig = hash_obj.hexdigest()[:8]
+	hex_dig_int = int(hex_dig, 16)
+	chk_be = binascii.hexlify(struct.pack('<I', hex_dig_int))
+	chk_be_int = int(chk_be, 16)
+    else:
+	chk_be_int = sum(map(ord, data))
 
+    header = struct.pack(header_format, size, chk_be_int,
+			 int("head".encode("hex"), 16), 0)
+    out_file.write(header + data)
 
 if __name__ == '__main__':
   main(sys.argv)