102 lines
3.4 KiB
Python
102 lines
3.4 KiB
Python
 
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#!/usr/bin/env python3
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"""Wrap the segments of an ESP8266 (v1) app image in a minimal ELF so binutils can read it.
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Reads only the app image (the 0x1000 slot of a full flash dump), never SPIFFS.
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python tools/esp8266_image_to_elf.py <full_dump.bin> <out.elf> [--offset 0x1000]
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Each image segment becomes one section (.irom0, .iram0_N, .dram0_N) at its load address,
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so `xtensa-lx106-elf-objdump -d out.elf` disassembles with real addresses.
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"""
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import argparse
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import struct
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APP_SLOT_MAX = 0x100000 # never read past the 1 MB app slot (SPIFFS starts at 0x200000)
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def read_segments(image):
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magic, nseg, _mode, _sizefreq, entry = struct.unpack_from("<BBBBI", image, 0)
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if magic != 0xE9:
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raise SystemExit(f"bad image magic 0x{magic:02x}")
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off = 8
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segs = []
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for _ in range(nseg):
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addr, size = struct.unpack_from("<II", image, off)
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off += 8
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segs.append((addr, image[off:off + size]))
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off += size
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return entry, segs
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def section_name(addr, counters):
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if 0x40200000 <= addr < 0x40300000:
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kind = "irom0"
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elif 0x40100000 <= addr < 0x40108000:
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kind = "iram0"
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else:
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kind = "dram0"
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counters[kind] = counters.get(kind, 0) + 1
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return f".{kind}_{counters[kind] - 1}"
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def build_elf(entry, segs):
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counters = {}
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names = [section_name(a, counters) for a, _ in segs]
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shstrtab = b"\0"
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name_off = []
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for n in names + [".shstrtab"]:
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name_off.append(len(shstrtab))
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shstrtab += n.encode() + b"\0"
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ehsize, phentsize, shentsize = 52, 32, 40
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nseg = len(segs)
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data_off = ehsize + phentsize * nseg
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body = b""
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offsets = []
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for _, data in segs:
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while (data_off + len(body)) % 4:
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body += b"\0"
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offsets.append(data_off + len(body))
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body += data
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shstr_off = data_off + len(body)
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body += shstrtab
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while (data_off + len(body)) % 4:
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body += b"\0"
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shoff = data_off + len(body)
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shnum = nseg + 2
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out = bytearray()
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out += b"\x7fELF" + bytes([1, 1, 1]) + bytes(9)
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out += struct.pack("<HHIIIIIHHHHHH", 2, 94, 1, entry, ehsize, shoff, 0x300,
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ehsize, phentsize, nseg, shentsize, shnum, shnum - 1)
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for (addr, data), o in zip(segs, offsets):
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flags = 5 if addr >= 0x40000000 else 6 # R+X for code, R+W for data
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out += struct.pack("<IIIIIIII", 1, o, addr, addr, len(data), len(data), flags, 4)
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out += body
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out += bytes(shentsize) # null section
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for i, ((addr, data), o) in enumerate(zip(segs, offsets)):
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code = addr >= 0x40000000
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sh_flags = 0x2 | (0x4 if code else 0x1) # ALLOC + EXECINSTR / WRITE
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out += struct.pack("<IIIIIIIIII", name_off[i], 1, sh_flags, addr, o, len(data), 0, 0, 4, 0)
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out += struct.pack("<IIIIIIIIII", name_off[-1], 3, 0, 0, shstr_off, len(shstrtab), 0, 0, 1, 0)
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return bytes(out)
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def main():
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ap = argparse.ArgumentParser(description=__doc__.splitlines()[0])
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ap.add_argument("dump")
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ap.add_argument("out")
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ap.add_argument("--offset", type=lambda s: int(s, 0), default=0x1000)
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args = ap.parse_args()
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with open(args.dump, "rb") as f:
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f.seek(args.offset)
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image = f.read(APP_SLOT_MAX - args.offset)
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entry, segs = read_segments(image)
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with open(args.out, "wb") as f:
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f.write(build_elf(entry, segs))
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for addr, data in segs:
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print(f"0x{addr:08x} 0x{len(data):06x}")
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if __name__ == "__main__":
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main()
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