module-debug.gdbinit

# Run GDB with "--init-command=module-debug.gdbinit". When you TCCLINK (or
# LOADMOD, or #REQUIRE) a module, a message will be printed on stdout
# containing something like "add-symbol-file-all <filename>.o
# 0x5555deadbeef". Paste that message into GDB and you will be able to debug
# the module just as if it were part of the main system.
# This has only been tested on AMD64, but it should also work on ARM with
# the allwinner-bare-metal GDB stub.
# Source: https://stackoverflow.com/questions/33049201/gdb-add-symbol-file-all-sections-and-load-address

python
import subprocess
import re

def relocatesections(filename, addr):
    p = subprocess.Popen(["readelf", "-S", filename], stdout = subprocess.PIPE)

    sections = []
    textaddr = '0'
    for line in p.stdout.readlines():
        line = line.decode("utf-8").strip()
        if not line.startswith('[') or line.startswith('[Nr]'):
            continue

        line = re.sub(r' +', ' ', line)
        line = re.sub(r'\[ *(\d+)\]', '\g<1>', line)
        fieldsvalue = line.split(' ')
        fieldsname = ['number', 'name', 'type', 'addr', 'offset', 'size', 'entsize', 'flags', 'link', 'info', 'addralign']
        sec = dict(zip(fieldsname, fieldsvalue))

        if sec['number'] == '0':
            continue

        sections.append(sec)

        if sec['name'] == '.text':
            textaddr = sec['addr']

    return (textaddr, sections)


class AddSymbolFileAll(gdb.Command):
    """The right version for add-symbol-file"""

    def __init__(self):
        super(AddSymbolFileAll, self).__init__("add-symbol-file-all", gdb.COMMAND_USER)
        self.dont_repeat()

    def invoke(self, arg, from_tty):
        argv = gdb.string_to_argv(arg)
        filename = argv[0]

        if len(argv) > 1:
            offset = int(str(gdb.parse_and_eval(argv[1])), 0)
        else:
            offset = 0

        (textaddr, sections) = relocatesections(filename, offset)

        cmd = "add-symbol-file %s 0x%08x" % (filename, int(textaddr, 16) + offset)

        for s in sections:
            addr = int(s['addr'], 16)
            if s['name'] == '.text' or addr == 0:
                continue

            cmd += " -s %s 0x%08x" % (s['name'], addr + offset)

        gdb.execute(cmd)

class RemoveSymbolFileAll(gdb.Command):
    """The right version for remove-symbol-file"""

    def __init__(self):
        super(RemoveSymbolFileAll, self).__init__("remove-symbol-file-all", gdb.COMMAND_USER)
        self.dont_repeat()

    def invoke(self, arg, from_tty):
        argv = gdb.string_to_argv(arg)
        filename = argv[0]

        if len(argv) > 1:
            offset = int(str(gdb.parse_and_eval(argv[1])), 0)
        else:
            offset = 0

        (textaddr, _) = relocatesections(filename, offset)

        cmd = "remove-symbol-file -a 0x%08x" % (int(textaddr, 16) + offset)
        gdb.execute(cmd)


AddSymbolFileAll()
RemoveSymbolFileAll()
end