diff options
Diffstat (limited to 'scripts/gdb/linux')
| -rw-r--r-- | scripts/gdb/linux/bpf.py | 253 | ||||
| -rw-r--r-- | scripts/gdb/linux/constants.py.in | 3 | ||||
| -rw-r--r-- | scripts/gdb/linux/radixtree.py | 139 | ||||
| -rw-r--r-- | scripts/gdb/linux/symbols.py | 105 |
4 files changed, 481 insertions, 19 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 diff --git a/scripts/gdb/linux/constants.py.in b/scripts/gdb/linux/constants.py.in index c3886739a028..6d475540c6ba 100644 --- a/scripts/gdb/linux/constants.py.in +++ b/scripts/gdb/linux/constants.py.in @@ -170,3 +170,6 @@ LX_CONFIG(CONFIG_PAGE_OWNER) LX_CONFIG(CONFIG_SLUB_DEBUG) LX_CONFIG(CONFIG_SLAB_FREELIST_HARDENED) LX_CONFIG(CONFIG_MMU) +LX_CONFIG(CONFIG_BPF) +LX_CONFIG(CONFIG_BPF_JIT) +LX_CONFIG(CONFIG_BPF_SYSCALL) diff --git a/scripts/gdb/linux/radixtree.py b/scripts/gdb/linux/radixtree.py index 074543ac763d..bc2954e45c32 100644 --- a/scripts/gdb/linux/radixtree.py +++ b/scripts/gdb/linux/radixtree.py @@ -30,13 +30,16 @@ def entry_to_node(node): def node_maxindex(node): return (constants.LX_RADIX_TREE_MAP_SIZE << node['shift']) - 1 -def lookup(root, index): +def resolve_root(root): + if root.type == radix_tree_root_type.get_type(): + return root if root.type == radix_tree_root_type.get_type().pointer(): - node = root.dereference() - elif root.type != radix_tree_root_type.get_type(): - raise gdb.GdbError("must be {} not {}" - .format(radix_tree_root_type.get_type(), root.type)) + return root.dereference() + raise gdb.GdbError("must be {} not {}" + .format(radix_tree_root_type.get_type(), root.type)) +def lookup(root, index): + root = resolve_root(root) node = root['xa_head'] if node == 0: return None @@ -71,14 +74,120 @@ def lookup(root, index): return node -class LxRadixTree(gdb.Function): +def descend(parent, index): + offset = (index >> int(parent["shift"])) & constants.LX_RADIX_TREE_MAP_MASK + return offset, parent["slots"][offset] + +def load_root(root): + node = root["xa_head"] + nodep = node + + if is_internal_node(node): + node = entry_to_node(node) + maxindex = node_maxindex(node) + return int(node["shift"]) + constants.LX_RADIX_TREE_MAP_SHIFT, \ + nodep, maxindex + + return 0, nodep, 0 + +class RadixTreeIter: + def __init__(self, start): + self.index = 0 + self.next_index = start + self.node = None + +def xa_mk_internal(v): + return (v << 2) | 2 + +LX_XA_RETRY_ENTRY = xa_mk_internal(256) +LX_RADIX_TREE_RETRY = LX_XA_RETRY_ENTRY + +def next_chunk(root, iter): + mask = (1 << (utils.get_ulong_type().sizeof * 8)) - 1 + + index = iter.next_index + if index == 0 and iter.index != 0: + return None + + restart = True + while restart: + restart = False + + _, child, maxindex = load_root(root) + if index > maxindex: + return None + if not child: + return None + + if not is_internal_node(child): + iter.index = index + iter.next_index = (maxindex + 1) & mask + iter.node = None + return root["xa_head"].address + + while True: + node = entry_to_node(child) + offset, child = descend(node, index) + + if not child: + while True: + offset += 1 + if offset >= constants.LX_RADIX_TREE_MAP_SIZE: + break + slot = node["slots"][offset] + if slot: + break + index &= ~node_maxindex(node) + index = (index + (offset << int(node["shift"]))) & mask + if index == 0: + return None + if offset == constants.LX_RADIX_TREE_MAP_SIZE: + restart = True + break + child = node["slots"][offset] + + if not child: + restart = True + break + if child == LX_XA_RETRY_ENTRY: + break + if not node["shift"] or not is_internal_node(child): + break + + iter.index = (index & ~node_maxindex(node)) | offset + iter.next_index = ((index | node_maxindex(node)) + 1) & mask + iter.node = node + + return node["slots"][offset].address + +def next_slot(slot, iter): + mask = (1 << (utils.get_ulong_type().sizeof * 8)) - 1 + for _ in range(iter.next_index - iter.index - 1): + slot += 1 + iter.index = (iter.index + 1) & mask + if slot.dereference(): + return slot + return None + +def for_each_slot(root, start=0): + iter = RadixTreeIter(start) + slot = None + while True: + if not slot: + slot = next_chunk(root, iter) + if not slot: + break + yield iter.index, slot + slot = next_slot(slot, iter) + +class LxRadixTreeLookup(gdb.Function): """ Lookup and return a node from a RadixTree. $lx_radix_tree_lookup(root_node [, index]): Return the node at the given index. If index is omitted, the root node is dereference and returned.""" def __init__(self): - super(LxRadixTree, self).__init__("lx_radix_tree_lookup") + super(LxRadixTreeLookup, self).__init__("lx_radix_tree_lookup") def invoke(self, root, index=0): result = lookup(root, index) @@ -87,4 +196,20 @@ If index is omitted, the root node is dereference and returned.""" return result +class LxRadixTree(gdb.Command): + """Show all values stored in a RadixTree.""" + + def __init__(self): + super(LxRadixTree, self).__init__("lx-radix-tree", gdb.COMMAND_DATA, + gdb.COMPLETE_NONE) + + def invoke(self, argument, from_tty): + args = gdb.string_to_argv(argument) + if len(args) != 1: + raise gdb.GdbError("Usage: lx-radix-tree ROOT") + root = gdb.parse_and_eval(args[0]) + for index, slot in for_each_slot(root): + gdb.write("[{}] = {}\n".format(index, slot.dereference())) + LxRadixTree() +LxRadixTreeLookup() diff --git a/scripts/gdb/linux/symbols.py b/scripts/gdb/linux/symbols.py index 6edb99221675..d4308b726183 100644 --- a/scripts/gdb/linux/symbols.py +++ b/scripts/gdb/linux/symbols.py @@ -11,13 +11,14 @@ # This work is licensed under the terms of the GNU GPL version 2. # +import atexit import gdb import os import re import struct from itertools import count -from linux import modules, utils, constants +from linux import bpf, constants, modules, utils if hasattr(gdb, 'Breakpoint'): @@ -114,17 +115,27 @@ class LxSymbols(gdb.Command): The kernel (vmlinux) is taken from the current working directly. Modules (.ko) are scanned recursively, starting in the same directory. Optionally, the module search path can be extended by a space separated list of paths passed to the -lx-symbols command.""" +lx-symbols command. + +When the -bpf flag is specified, symbols from the currently loaded BPF programs +are loaded as well.""" module_paths = [] module_files = [] module_files_updated = False loaded_modules = [] breakpoint = None + bpf_prog_monitor = None + bpf_ksym_monitor = None + bpf_progs = {} + # The remove-symbol-file command, even when invoked with -a, requires the + # respective object file to exist, so keep them around. + bpf_debug_objs = {} def __init__(self): super(LxSymbols, self).__init__("lx-symbols", gdb.COMMAND_FILES, gdb.COMPLETE_FILENAME) + atexit.register(self.cleanup_bpf) def _update_module_files(self): self.module_files = [] @@ -197,6 +208,51 @@ lx-symbols command.""" else: gdb.write("no module object found for '{0}'\n".format(module_name)) + def add_bpf_prog(self, prog): + if prog["jited"]: + self.bpf_progs[int(prog["bpf_func"])] = prog + + def remove_bpf_prog(self, prog): + self.bpf_progs.pop(int(prog["bpf_func"]), None) + + def add_bpf_ksym(self, ksym): + addr = int(ksym["start"]) + name = bpf.get_ksym_name(ksym) + with utils.pagination_off(): + gdb.write("loading @{addr}: {name}\n".format( + addr=hex(addr), name=name)) + debug_obj = bpf.generate_debug_obj(ksym, self.bpf_progs.get(addr)) + if debug_obj is None: + return + try: + cmdline = "add-symbol-file {obj} {addr}".format( + obj=debug_obj.name, addr=hex(addr)) + gdb.execute(cmdline, to_string=True) + except: + debug_obj.close() + raise + self.bpf_debug_objs[addr] = debug_obj + + def remove_bpf_ksym(self, ksym): + addr = int(ksym["start"]) + debug_obj = self.bpf_debug_objs.pop(addr, None) + if debug_obj is None: + return + try: + name = bpf.get_ksym_name(ksym) + gdb.write("unloading @{addr}: {name}\n".format( + addr=hex(addr), name=name)) + cmdline = "remove-symbol-file {path}".format(path=debug_obj.name) + gdb.execute(cmdline, to_string=True) + finally: + debug_obj.close() + + def cleanup_bpf(self): + self.bpf_progs = {} + while len(self.bpf_debug_objs) > 0: + self.bpf_debug_objs.popitem()[1].close() + + def load_all_symbols(self): gdb.write("loading vmlinux\n") @@ -224,34 +280,59 @@ lx-symbols command.""" else: [self.load_module_symbols(module) for module in module_list] + self.cleanup_bpf() + if self.bpf_prog_monitor is not None: + self.bpf_prog_monitor.notify_initial() + if self.bpf_ksym_monitor is not None: + self.bpf_ksym_monitor.notify_initial() + for saved_state in saved_states: saved_state['breakpoint'].enabled = saved_state['enabled'] def invoke(self, arg, from_tty): skip_decompressor() - self.module_paths = [os.path.abspath(os.path.expanduser(p)) - for p in arg.split()] + monitor_bpf = False + self.module_paths = [] + for p in arg.split(): + if p == "-bpf": + monitor_bpf = True + else: + p.append(os.path.abspath(os.path.expanduser(p))) self.module_paths.append(os.getcwd()) + if self.breakpoint is not None: + self.breakpoint.delete() + self.breakpoint = None + if self.bpf_prog_monitor is not None: + self.bpf_prog_monitor.delete() + self.bpf_prog_monitor = None + if self.bpf_ksym_monitor is not None: + self.bpf_ksym_monitor.delete() + self.bpf_ksym_monitor = None + # enforce update self.module_files = [] self.module_files_updated = False self.load_all_symbols() - if not modules.has_modules(): + if not hasattr(gdb, 'Breakpoint'): + gdb.write("Note: symbol update on module and BPF loading not " + "supported with this gdb version\n") return - if hasattr(gdb, 'Breakpoint'): - if self.breakpoint is not None: - self.breakpoint.delete() - self.breakpoint = None + if modules.has_modules(): self.breakpoint = LoadModuleBreakpoint( "kernel/module/main.c:do_init_module", self) - else: - gdb.write("Note: symbol update on module loading not supported " - "with this gdb version\n") + + if monitor_bpf: + if constants.LX_CONFIG_BPF_SYSCALL: + self.bpf_prog_monitor = bpf.ProgMonitor(self.add_bpf_prog, + self.remove_bpf_prog) + if constants.LX_CONFIG_BPF and constants.LX_CONFIG_BPF_JIT: + self.bpf_ksym_monitor = bpf.KsymMonitor(self.add_bpf_ksym, + self.remove_bpf_ksym) LxSymbols() |