1#!/usr/bin/env python3
2#
3# Copyright (c) 2024 Meta Platforms
4#
5# SPDX-License-Identifier: Apache-2.0
6
7import argparse
8import os
9import re
10import sys
11
12from elftools.elf.descriptions import (
13    describe_symbol_type,
14)
15from elftools.elf.elffile import ELFFile
16
17
18class gen_symtab_log:
19    def __init__(self, debug=False):
20        self.__debug = debug
21
22    def debug(self, text):
23        """Print debug message if debugging is enabled.
24
25        Note - this function requires config global variable to be initialized.
26        """
27        if self.__debug:
28            sys.stdout.write(os.path.basename(sys.argv[0]) + ": " + text + "\n")
29
30    @staticmethod
31    def error(text):
32        sys.exit(os.path.basename(sys.argv[0]) + ": error: " + text + "\n")
33
34    def set_debug(self, state):
35        self.__debug = state
36
37
38log = gen_symtab_log()
39
40
41def parse_args():
42    parser = argparse.ArgumentParser(
43        description=__doc__,
44        formatter_class=argparse.RawDescriptionHelpFormatter,
45        allow_abbrev=False,
46    )
47
48    parser.add_argument("-k", "--kernel", required=True, help="Zephyr kernel image")
49    parser.add_argument("-o", "--output", required=True, help="Output source file")
50    parser.add_argument(
51        "-d", "--debug", action="store_true", help="Print additional debugging information"
52    )
53
54    return parser.parse_args()
55
56
57class symtab_entry:
58    def __init__(self, addr, size, offset, name):
59        self.addr = addr
60        self.size = size
61        self.offset = offset
62        self.name = name
63
64    def __eq__(self, other):
65        return self.addr == other.addr
66
67
68first_addr = 0
69symtab_list = []
70
71
72def sanitize_func_name(name):
73    pattern = r'(^[a-zA-Z_][a-zA-Z0-9_]*)'
74    match = re.match(pattern, name)
75    if match:
76        return match.group(0)
77    else:
78        log.error(f"Failed to sanitize function name: {name}")
79
80    return name
81
82
83def main():
84    args = parse_args()
85    log.set_debug(args.debug)
86
87    with open(args.kernel, "rb") as rf:
88        elf = ELFFile(rf)
89
90        # Find the symbol table.
91        symtab = elf.get_section_by_name('.symtab')
92
93        for symbol in symtab.iter_symbols():
94            symbol_type = describe_symbol_type(symbol['st_info']['type'])
95            symbol_addr = symbol['st_value']
96            symbol_size = symbol['st_size']
97
98            if symbol_type == 'FUNC' and symbol_addr != 0:
99                symbol_name = sanitize_func_name(symbol.name)
100                dummy_offset = 0  # offsets will be calculated later after we know the first address
101                entry = symtab_entry(symbol_addr, symbol_size, dummy_offset, symbol_name)
102                # Prevent entries with duplicated addresses
103                if entry not in symtab_list:
104                    symtab_list.append(entry)
105
106        # Sort the address in ascending order
107        symtab_list.sort(key=lambda x: x.addr, reverse=False)
108
109        # Get the address of the first symbol
110        first_addr = symtab_list[0].addr
111
112        for i, entry in enumerate(symtab_list):
113            # Offset is calculated here
114            entry.offset = entry.addr - first_addr
115
116            # Debug print
117            log.debug(f'{i:6d}: {hex(entry.addr)} {hex(entry.size)} {entry.name:.25s}')
118
119    with open(args.output, 'w') as wf:
120        print("/* AUTO-GENERATED by gen_symtab.py, do not edit! */", file=wf)
121        print("", file=wf)
122        print("#include <zephyr/linker/sections.h>", file=wf)
123        print("#include <zephyr/debug/symtab.h>", file=wf)
124        print("", file=wf)
125        num = len(symtab_list) + 1
126        print(
127            f"const struct z_symtab_entry __symtab_entry z_symtab_entries[{num}] = {{",
128            file=wf,
129        )
130        for i, entry in enumerate(symtab_list):
131            print(f"\t/* ADDR: {hex(entry.addr)} SIZE: {hex(entry.size)} */", file=wf)
132            print(
133                f"\t[{i}] = {{.offset = {hex(entry.offset)}, .name = \"{entry.name}\"}},", file=wf
134            )
135
136        # Append a dummy entry at the end to facilitate the binary search
137        if symtab_list[-1].size == 0:
138            dummy_offset = f"{hex(symtab_list[-1].offset)} + sizeof(uintptr_t)"
139        else:
140            dummy_offset = f"{hex(symtab_list[-1].offset + symtab_list[-1].size)}"
141        print("\t/* dummy entry */", file=wf)
142        print(f"\t[{len(symtab_list)}] = {{.offset = {dummy_offset}, .name = \"?\"}},", file=wf)
143        print("};\n", file=wf)
144
145        print("const struct symtab_info __symtab_info z_symtab = {", file=wf)
146        print(f"\t.first_addr = {hex(first_addr)},", file=wf)
147        print(f"\t.length = {len(symtab_list)},", file=wf)
148        print("\t.entries = z_symtab_entries,", file=wf)
149        print("};\n", file=wf)
150
151
152if __name__ == "__main__":
153    main()
154