diff options
Diffstat (limited to 'scripts/gdb/linux/bpf.py')
| -rw-r--r-- | scripts/gdb/linux/bpf.py | 253 |
1 files changed, 253 insertions, 0 deletions
diff --git a/scripts/gdb/linux/bpf.py b/scripts/gdb/linux/bpf.py new file mode 100644 index 000000000000..1870534ef6f9 --- /dev/null +++ b/scripts/gdb/linux/bpf.py @@ -0,0 +1,253 @@ +# SPDX-License-Identifier: GPL-2.0 + +import json +import subprocess +import tempfile + +import gdb + +from linux import constants, lists, radixtree, utils + + +if constants.LX_CONFIG_BPF and constants.LX_CONFIG_BPF_JIT: + bpf_ksym_type = utils.CachedType("struct bpf_ksym") +if constants.LX_CONFIG_BPF_SYSCALL: + bpf_prog_type = utils.CachedType("struct bpf_prog") + + +def get_ksym_name(ksym): + name = ksym["name"].bytes + end = name.find(b"\x00") + if end != -1: + name = name[:end] + return name.decode() + + +def list_ksyms(): + if not (constants.LX_CONFIG_BPF and constants.LX_CONFIG_BPF_JIT): + return [] + bpf_kallsyms = gdb.parse_and_eval("&bpf_kallsyms") + bpf_ksym_ptr_type = bpf_ksym_type.get_type().pointer() + return list(lists.list_for_each_entry(bpf_kallsyms, + bpf_ksym_ptr_type, + "lnode")) + + +class KsymAddBreakpoint(gdb.Breakpoint): + def __init__(self, monitor): + super(KsymAddBreakpoint, self).__init__("bpf_ksym_add", internal=True) + self.silent = True + self.monitor = monitor + + def stop(self): + self.monitor.add(gdb.parse_and_eval("ksym")) + return False + + +class KsymRemoveBreakpoint(gdb.Breakpoint): + def __init__(self, monitor): + super(KsymRemoveBreakpoint, self).__init__("bpf_ksym_del", + internal=True) + self.silent = True + self.monitor = monitor + + def stop(self): + self.monitor.remove(gdb.parse_and_eval("ksym")) + return False + + +class KsymMonitor: + def __init__(self, add, remove): + self.add = add + self.remove = remove + + self.add_bp = KsymAddBreakpoint(self) + self.remove_bp = KsymRemoveBreakpoint(self) + + self.notify_initial() + + def notify_initial(self): + for ksym in list_ksyms(): + self.add(ksym) + + def delete(self): + self.add_bp.delete() + self.remove_bp.delete() + + +def list_progs(): + if not constants.LX_CONFIG_BPF_SYSCALL: + return [] + idr_rt = gdb.parse_and_eval("&prog_idr.idr_rt") + bpf_prog_ptr_type = bpf_prog_type.get_type().pointer() + progs = [] + for _, slot in radixtree.for_each_slot(idr_rt): + prog = slot.dereference().cast(bpf_prog_ptr_type) + progs.append(prog) + # Subprogs are not registered in prog_idr, fetch them manually. + # func[0] is the current prog. + aux = prog["aux"] + func = aux["func"] + real_func_cnt = int(aux["real_func_cnt"]) + for i in range(1, real_func_cnt): + progs.append(func[i]) + return progs + + +class ProgAddBreakpoint(gdb.Breakpoint): + def __init__(self, monitor): + super(ProgAddBreakpoint, self).__init__("bpf_prog_kallsyms_add", + internal=True) + self.silent = True + self.monitor = monitor + + def stop(self): + self.monitor.add(gdb.parse_and_eval("fp")) + return False + + +class ProgRemoveBreakpoint(gdb.Breakpoint): + def __init__(self, monitor): + super(ProgRemoveBreakpoint, self).__init__("bpf_prog_free_id", + internal=True) + self.silent = True + self.monitor = monitor + + def stop(self): + self.monitor.remove(gdb.parse_and_eval("prog")) + return False + + +class ProgMonitor: + def __init__(self, add, remove): + self.add = add + self.remove = remove + + self.add_bp = ProgAddBreakpoint(self) + self.remove_bp = ProgRemoveBreakpoint(self) + + self.notify_initial() + + def notify_initial(self): + for prog in list_progs(): + self.add(prog) + + def delete(self): + self.add_bp.delete() + self.remove_bp.delete() + + +def btf_str_by_offset(btf, offset): + while offset < btf["start_str_off"]: + btf = btf["base_btf"] + + offset -= btf["start_str_off"] + if offset < btf["hdr"]["str_len"]: + return (btf["strings"] + offset).string() + + return None + + +def bpf_line_info_line_num(line_col): + return line_col >> 10 + + +def bpf_line_info_line_col(line_col): + return line_col & 0x3ff + + +class LInfoIter: + def __init__(self, prog): + # See bpf_prog_get_file_line() for details. + self.pos = 0 + self.nr_linfo = 0 + + if prog is None: + return + + self.bpf_func = int(prog["bpf_func"]) + aux = prog["aux"] + self.btf = aux["btf"] + linfo_idx = aux["linfo_idx"] + self.nr_linfo = int(aux["nr_linfo"]) - linfo_idx + if self.nr_linfo == 0: + return + + linfo_ptr = aux["linfo"] + tpe = linfo_ptr.type.target().array(self.nr_linfo).pointer() + self.linfo = (linfo_ptr + linfo_idx).cast(tpe).dereference() + jited_linfo_ptr = aux["jited_linfo"] + tpe = jited_linfo_ptr.type.target().array(self.nr_linfo).pointer() + self.jited_linfo = (jited_linfo_ptr + linfo_idx).cast(tpe).dereference() + + self.filenos = {} + + def get_code_off(self): + if self.pos >= self.nr_linfo: + return -1 + return self.jited_linfo[self.pos] - self.bpf_func + + def advance(self): + self.pos += 1 + + def get_fileno(self): + file_name_off = int(self.linfo[self.pos]["file_name_off"]) + fileno = self.filenos.get(file_name_off) + if fileno is not None: + return fileno, None + file_name = btf_str_by_offset(self.btf, file_name_off) + fileno = len(self.filenos) + 1 + self.filenos[file_name_off] = fileno + return fileno, file_name + + def get_line_col(self): + line_col = int(self.linfo[self.pos]["line_col"]) + return bpf_line_info_line_num(line_col), \ + bpf_line_info_line_col(line_col) + + +def generate_debug_obj(ksym, prog): + name = get_ksym_name(ksym) + # Avoid read_memory(); it throws bogus gdb.MemoryError in some contexts. + start = ksym["start"] + code = start.cast(gdb.lookup_type("unsigned char") + .array(int(ksym["end"]) - int(start)) + .pointer()).dereference().bytes + linfo_iter = LInfoIter(prog) + + result = tempfile.NamedTemporaryFile(suffix=".o", mode="wb") + try: + with tempfile.NamedTemporaryFile(suffix=".s", mode="w") as src: + # ".loc" does not apply to ".byte"s, only to ".insn"s, but since + # this needs to work for all architectures, the latter are not an + # option. Ask the assembler to apply ".loc"s to labels as well, + # and generate dummy labels after each ".loc". + src.write(".loc_mark_labels 1\n") + + src.write(".globl {}\n".format(name)) + src.write(".type {},@function\n".format(name)) + src.write("{}:\n".format(name)) + for code_off, code_byte in enumerate(code): + if linfo_iter.get_code_off() == code_off: + fileno, file_name = linfo_iter.get_fileno() + if file_name is not None: + src.write(".file {} {}\n".format( + fileno, json.dumps(file_name))) + line, col = linfo_iter.get_line_col() + src.write(".loc {} {} {}\n".format(fileno, line, col)) + src.write("0:\n") + linfo_iter.advance() + src.write(".byte {}\n".format(code_byte)) + src.write(".size {},{}\n".format(name, len(code))) + src.flush() + + try: + subprocess.check_call(["as", "-c", src.name, "-o", result.name]) + except FileNotFoundError: + # "as" is not installed. + result.close() + return None + return result + except: + result.close() + raise |