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Justin C. Miller
e7f9d8f1d7
Create a script that builds a simple-to-read symbol table from the output of `nm`. Include running that script over the kernel in the build, and including that output in the initrd. Tags: callstack debugging
72 lines
1.8 KiB
Python
Executable File
72 lines
1.8 KiB
Python
Executable File
#!/usr/bin/env python3
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#
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# Generate the jsix style symbol table. The format in memory of this table
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# is as follows:
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#
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# <num_entires> : 8 bytes
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# <index> : 16 * N bytes
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# <name data> : variable
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#
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# Each index entry has the format
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# <symbol address> : 8 bytes
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# <offset of name> : 8 bytes
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#
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# Name offsets are from the start of the symbol table as a whole. (ie,
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# where <num_entries> is located.)
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def parse_syms(infile):
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"""Take the output of the `nm` command, and parse it into a tuple
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representing the symbols in the text segment of the binary. Returns
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a list of (address, symbol_name)."""
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from cxxfilt import demangle
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syms = []
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for line in sys.stdin:
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addr, t, mangled = line.split()
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if t not in "tTvVwW": continue
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addr = int(addr, base=16)
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name = demangle(mangled)
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syms.append((addr, name))
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return sorted(syms)
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def write_table(syms, outfile):
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"""Write the given symbol table as generated by parse_syms()
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to the outfile, index first, and then name character data."""
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import struct
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outfile.write(struct.pack("@Q", len(syms)))
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index_pos = outfile.tell()
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outfile.seek(struct.calcsize("@QQ") * len(syms), 1)
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nul = b'\0'
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positions = {}
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for s in syms:
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addr, name = s
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positions[addr] = outfile.tell()
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data = name.encode('utf-8')
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outfile.write(name.encode('utf-8'))
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outfile.write(nul)
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outfile.seek(index_pos)
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for s in syms:
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addr = s[0]
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pos = positions[addr]
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outfile.write(struct.pack("@QQ", addr, pos))
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if __name__ == "__main__":
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import sys
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if len(sys.argv) != 2:
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print(f"Usage: {sys.argv[0]} <output>")
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sys.exit(1)
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outfile = open(sys.argv[1], "wb")
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write_table(parse_syms(sys.stdin), outfile)
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