hwpatcher: add generic RKW file patching script

This script is handy hacking tool to patch RKW file with
arbitrary binary and put jump into implanted code.
It also shows how to use hwstub crc routine.

Change-Id: I89b5086dc1ddaca3dbc03df26a85472d8a20d51e

utils/hwpatcher/rkwpatch.lua

@@ -0,0 +1,126 @@
+--[[
+RKW patching tool
+required argument (in order):
+- path to rkw
+- path to stub
+- physical address where to put bin blob
+- physical address where to put jump
+- path to output patched firmware
+]]-- 
+require("lib")
+require("arm")
+
+function printf(...)
+    io.write(string.format(...))
+end
+
+if #arg < 5 then
+    printf("Arguments: source.rkw blob.bin blob_address jump_address output.rkw\n")
+    printf("source.rkw\tRKW file to be patched\n")
+    printf("blob.bin\tArbitrary binary to be implanted (e.g hwstub.bin)\n")
+    printf("blob_address\tPhysical address where to implant blob (e.g 0x6008300c)\n")
+    printf("jump_address\tPhysical address where to put jump to implanted binary (e.g 0x60097f2c)\n")
+    printf("output.rkw\tResulting RKW file\n")
+    os.exit(1)
+end
+
+-- return rkw file offset based on physical runtime mem addr
+-- sdram base address is 0x60000000 and rkw header is 0x2c long
+function addr2rkw(addr)
+    return (addr + 0x2c - 0x60000000)
+end
+
+-- read input file
+local fw = hwp.load_file(arg[1])
+
+-- read and check RKW magic number
+local rkw_magic = hwp.read32(fw, hwp.make_addr(0))
+
+if rkw_magic ~=  0x4c44524b then
+    printf("error: wrong RKW magic number\n")
+    os.exit(1)
+end
+
+-- check RKW header size
+local rkw_header_size = hwp.read32(fw, hwp.make_addr(0x04))
+
+if rkw_header_size ~= 0x2c then
+    printf("error: RKW header size 0x%0x should be 0x2c!\n", rkw_header_size)
+    os.exit(1)
+end
+
+-- check RKW header CRC
+local header_crc = hwp.crc(RKW, fw, hwp.make_addr(0), 0x28)
+
+if hwp.read32(fw, hwp.make_addr(0x28)) ~= header_crc then
+    printf("error: RKW header CRC mismatch\n")
+    os.exit(1)
+end
+
+local firmware_blob = hwp.make_addr(rkw_header_size)
+local blob_size = hwp.read32(fw, hwp.make_addr(0x10)) - hwp.read32(fw, hwp.make_addr(0x8))
+local rkw_crc = 0
+
+-- check if blob has CRC attached
+if blob_size < hwp.section_info(fw, "").size then
+    rkw_crc = hwp.crc(RKW, fw, firmware_blob, blob_size)
+
+    if hwp.read32(fw, hwp.make_addr(blob_size+rkw_header_size)) ~= rkw_crc then
+        printf("error: RKW CRC mismatch\n")
+        os.exit(1)
+    end
+else
+    printf("error: blob reported size: 0x%0x >= actual blob size: 0x%0x\n", blob_size, hwp.section_info(fw, "").size)
+    os.exit(1)
+end
+
+printf("RKW sanity checks passed\n")
+printf("RKW magic:\t0x%0x\n", rkw_magic)
+printf("Header size:\t0x%0x\n", rkw_header_size)
+printf("Image Base:\t0x%0x\n", hwp.read32(fw, hwp.make_addr(0x8)))
+printf("Load Base:\t0x%0x\n", hwp.read32(fw, hwp.make_addr(0xc)))
+printf("Load Limit:\t0x%0x\n", hwp.read32(fw, hwp.make_addr(0x10)))
+printf("ZI Base:\t0x%0x\n", hwp.read32(fw, hwp.make_addr(0x14)))
+printf("Entry point:\t0x%0x\n", hwp.read32(fw, hwp.make_addr(0x20)))
+printf("Load flags:\t0x%0x\n", hwp.read32(fw, hwp.make_addr(0x24)))
+printf("Header crc:\t0x%0x\n", header_crc)
+printf("Blob crc:\t0x%0x\n", rkw_crc)
+
+-- branch instruction
+local jump_instr_addr = hwp.make_addr(addr2rkw(arg[4]))
+if (jump_instr_addr == nil) then
+    printf("error: invalid jump instruction address\n")
+    os.exit(1)
+end
+
+local stub_addr = hwp.make_addr(addr2rkw(arg[3])) -- some decoder stuff
+if (stub_addr == nil) then
+    printf("error: invalid blob implant address\n")
+    os.exit(1)
+end
+
+-- put stub at the right place
+local stub = hwp.load_bin_file(arg[2])
+if (stub == nil) then
+    printf("error: can't load blob file: %s\n", arg[2])
+    os.exit(1)
+end
+
+local stub_info = hwp.section_info(stub, "")
+local stub_data = hwp.read(stub, hwp.make_addr(stub_info.addr, ""), stub_info.size)
+hwp.write(fw, stub_addr, stub_data)
+printf("Implanting blob at: 0x%0x\n", arg[3])
+
+-- patch jump
+local branch_to_stub = arm.make_branch(arm.to_arm(stub_addr), false)
+arm.write_branch(fw, jump_instr_addr, branch_to_stub, hwp.inc_addr(stub_addr, stub_info.size))
+printf("Patching jump instruction at: 0x%0x\n", arg[4])
+
+-- patch rkw crc
+rkw_crc = hwp.crc(RKW, fw, firmware_blob, blob_size)
+printf("Patching RKW with new CRC: 0x%0x\n", rkw_crc)
+hwp.write32(fw, hwp.make_addr(blob_size+rkw_header_size), rkw_crc)
+
+-- save
+hwp.save_file(fw, arg[5])
+printf("Saving output to: '%s'\n", arg[5])