debug: implement symtab generation
Use pyelftools to extract the symbol table from the
link stage executable. Then, filter out the function names
and sort them based on their offsets before writing into the
`symtab.c`, this is similar to how the `isr_tables` works.
To access the structure, simply include the new header:
```c
#include <zephyr/debug/symtab.h>
```
Signed-off-by: Yong Cong Sin <ycsin@meta.com>
diff --git a/scripts/build/gen_symtab.py b/scripts/build/gen_symtab.py
new file mode 100644
index 0000000..a2c767c
--- /dev/null
+++ b/scripts/build/gen_symtab.py
@@ -0,0 +1,119 @@
+#!/usr/bin/env python3
+#
+# Copyright (c) 2024 Meta Platforms
+#
+# SPDX-License-Identifier: Apache-2.0
+
+import argparse
+import sys
+import os
+
+from elftools.elf.elffile import ELFFile
+from elftools.elf.descriptions import (
+ describe_symbol_type,
+)
+
+
+class gen_symtab_log:
+
+ def __init__(self, debug=False):
+ self.__debug = debug
+
+ def debug(self, text):
+ """Print debug message if debugging is enabled.
+
+ Note - this function requires config global variable to be initialized.
+ """
+ if self.__debug:
+ sys.stdout.write(os.path.basename(
+ sys.argv[0]) + ": " + text + "\n")
+
+ @staticmethod
+ def error(text):
+ sys.exit(os.path.basename(sys.argv[0]) + ": error: " + text + "\n")
+
+ def set_debug(self, state):
+ self.__debug = state
+
+
+log = gen_symtab_log()
+
+
+def parse_args():
+ parser = argparse.ArgumentParser(description=__doc__,
+ formatter_class=argparse.RawDescriptionHelpFormatter, allow_abbrev=False)
+
+ parser.add_argument("-k", "--kernel", required=True,
+ help="Zephyr kernel image")
+ parser.add_argument("-o", "--output", required=True,
+ help="Output source file")
+ parser.add_argument("-d", "--debug", action="store_true",
+ help="Print additional debugging information")
+
+ return parser.parse_args()
+
+
+class symtab_entry:
+ def __init__(self, addr, offset, name):
+ self.addr = addr
+ self.offset = offset
+ self.name = name
+
+
+start_addr = 0
+symtab_list = []
+
+
+def main():
+ args = parse_args()
+ log.set_debug(args.debug)
+
+ with open(args.kernel, "rb") as rf:
+ elf = ELFFile(rf)
+
+ # Find the symbol table.
+ symtab = elf.get_section_by_name('.symtab')
+
+ i = 1
+ for nsym, symbol in enumerate(symtab.iter_symbols()): # pylint: disable=unused-variable
+ symbol_type = describe_symbol_type(symbol['st_info']['type'])
+ symbol_addr = symbol['st_value']
+
+ if symbol_type == 'FUNC' and symbol_addr != 0:
+ symtab_list.append(symtab_entry(
+ symbol_addr, symbol_addr, symbol.name))
+ log.debug('%6d: %s %.25s' % (
+ i,
+ hex(symbol_addr),
+ symbol.name))
+ i = i + 1
+
+ symtab_list.sort(key=lambda x: x.addr, reverse=False)
+
+ # Get the address of the first symbol
+ start_addr = symtab_list[0].addr
+ # Use that to calculate the offset of other symbols relative to the first one
+ for i, entry in enumerate(symtab_list):
+ entry.offset = entry.addr - start_addr
+
+ with open(args.output, 'w') as wf:
+ print("/* AUTO-GENERATED by gen_symtab.py, do not edit! */", file=wf)
+ print("", file=wf)
+ print("#include <zephyr/debug/symtab.h>", file=wf)
+ print("", file=wf)
+ print(
+ f"const struct z_symtab_entry z_symtab_entries[{len(symtab_list)}] = {{", file=wf)
+ for i, entry in enumerate(symtab_list):
+ print(
+ f"\t[{i}] = {{.offset = {hex(entry.offset)}, .name = \"{entry.name}\"}}, /* {hex(entry.addr)} */", file=wf)
+ print(f"}};\n", file=wf)
+
+ print(f"const struct symtab_info z_symtab = {{", file=wf)
+ print(f"\t.start_addr = {hex(start_addr)},", file=wf)
+ print(f"\t.length = {len(symtab_list)},", file=wf)
+ print(f"\t.entries = z_symtab_entries,", file=wf)
+ print(f"}};\n", file=wf)
+
+
+if __name__ == "__main__":
+ main()
