[U-Boot] [PATCH v3 1/2] rockchip: make_fit_atf.py: Eliminate pyelftools dependency

[Chris Webb <chris@arachsys.com>]

make_fit_aft.py depends on the non-standard library pyelftools to pull
out PT_LOAD segments from ELF files. However, this is as easy to do
manually, without imposing the extra dependency on users.

Structures in the ELF file are unpacked into variables named to exactly
match the ELF spec to ensure the destructuring code is reasonably
self-documenting.

Signed-off-by: Chris Webb <chris@arachsys.com>
---
 arch/arm/mach-rockchip/make_fit_atf.py | 75 +++++++++++---------------
 1 file changed, 32 insertions(+), 43 deletions(-)

diff --git a/arch/arm/mach-rockchip/make_fit_atf.py b/arch/arm/mach-rockchip/make_fit_atf.py
index db0ae96ca8..b9a1988298 100755
--- a/arch/arm/mach-rockchip/make_fit_atf.py
+++ b/arch/arm/mach-rockchip/make_fit_atf.py
@@ -13,16 +13,7 @@ import os
 import sys
 import getopt
 import logging
-
-# pip install pyelftools
-from elftools.elf.elffile import ELFFile
-
-ELF_SEG_P_TYPE = 'p_type'
-ELF_SEG_P_PADDR = 'p_paddr'
-ELF_SEG_P_VADDR = 'p_vaddr'
-ELF_SEG_P_OFFSET = 'p_offset'
-ELF_SEG_P_FILESZ = 'p_filesz'
-ELF_SEG_P_MEMSZ = 'p_memsz'
+import struct
 
 DT_HEADER = """
 /*
@@ -118,33 +109,19 @@ def append_conf_node(file, dtbs, segments):
     file.write('\n')
 
 def generate_atf_fit_dts_uboot(fit_file, uboot_file_name):
-    num_load_seg = 0
-    p_paddr = 0xFFFFFFFF
-    with open(uboot_file_name, 'rb') as uboot_file:
-        uboot = ELFFile(uboot_file)
-        for i in range(uboot.num_segments()):
-            seg = uboot.get_segment(i)
-            if seg.__getitem__(ELF_SEG_P_TYPE) == 'PT_LOAD':
-                p_paddr = seg.__getitem__(ELF_SEG_P_PADDR)
-                num_load_seg = num_load_seg + 1
-
-    assert (p_paddr != 0xFFFFFFFF and num_load_seg == 1)
-
+    segments = unpack_elf(uboot_file_name)
+    if len(segments) != 1:
+        raise ValueError("Invalid u-boot ELF image '%s'" % uboot_file_name)
+    index, entry, p_paddr, data = segments[0]
     fit_file.write(DT_UBOOT % p_paddr)
 
 def generate_atf_fit_dts_bl31(fit_file, bl31_file_name, dtbs_file_name):
-    with open(bl31_file_name, 'rb') as bl31_file:
-        bl31 = ELFFile(bl31_file)
-        elf_entry = bl31.header['e_entry']
-        segments = bl31.num_segments()
-        for i in range(segments):
-            seg = bl31.get_segment(i)
-            if seg.__getitem__(ELF_SEG_P_TYPE) == 'PT_LOAD':
-                paddr = seg.__getitem__(ELF_SEG_P_PADDR)
-                append_bl31_node(fit_file, i + 1, paddr, elf_entry)
+    segments = unpack_elf(bl31_file_name)
+    for index, entry, paddr, data in segments:
+        append_bl31_node(fit_file, index + 1, paddr, entry)
     append_fdt_node(fit_file, dtbs_file_name)
     fit_file.write(DT_IMAGES_NODE_END)
-    append_conf_node(fit_file, dtbs_file_name, segments)
+    append_conf_node(fit_file, dtbs_file_name, len(segments))
 
 def generate_atf_fit_dts(fit_file_name, bl31_file_name, uboot_file_name, dtbs_file_name):
     # Generate FIT script for ATF image.
@@ -162,17 +139,29 @@ def generate_atf_fit_dts(fit_file_name, bl31_file_name, uboot_file_name, dtbs_fi
         fit_file.close()
 
 def generate_atf_binary(bl31_file_name):
-    with open(bl31_file_name, 'rb') as bl31_file:
-        bl31 = ELFFile(bl31_file)
-
-        num = bl31.num_segments()
-        for i in range(num):
-            seg = bl31.get_segment(i)
-            if seg.__getitem__(ELF_SEG_P_TYPE) == 'PT_LOAD':
-                paddr = seg.__getitem__(ELF_SEG_P_PADDR)
-                file_name = 'bl31_0x%08x.bin' % paddr
-                with open(file_name, "wb") as atf:
-                    atf.write(seg.data())
+    for index, entry, paddr, data in unpack_elf(bl31_file_name):
+        file_name = 'bl31_0x%08x.bin' % paddr
+        with open(file_name, "wb") as atf:
+            atf.write(data)
+
+def unpack_elf(filename):
+    with open(filename, 'rb') as file:
+        elf = file.read()
+    if elf[0:7] != b'\x7fELF\x02\x01\x01' or elf[18:20] != b'\xb7\x00':
+        raise ValueError("Invalid arm64 ELF file '%s'" % filename)
+
+    e_entry, e_phoff = struct.unpack_from('<2Q', elf, 0x18)
+    e_phentsize, e_phnum = struct.unpack_from('<2H', elf, 0x36)
+    segments = []
+
+    for index in range(e_phnum):
+        offset = e_phoff + e_phentsize * index
+        p_type, p_flags, p_offset = struct.unpack_from('<LLQ', elf, offset)
+        if p_type == 1: # PT_LOAD
+            p_paddr, p_filesz = struct.unpack_from('<2Q', elf, offset + 0x18)
+            p_data = elf[p_offset:p_offset + p_filesz]
+            segments.append((index, e_entry, p_paddr, p_data))
+    return segments
 
 def main():
     uboot_elf = "./u-boot"