| #!/usr/bin/env python |
| # |
| # trace Trace a function and print a trace message based on its |
| # parameters, with an optional filter. |
| # |
| # usage: trace [-h] [-p PID] [-L TID] [-v] [-Z STRING_SIZE] [-S] |
| # [-M MAX_EVENTS] [-T] [-t] [-K] [-U] [-a] [-I header] |
| # probe [probe ...] |
| # |
| # Licensed under the Apache License, Version 2.0 (the "License") |
| # Copyright (C) 2016 Sasha Goldshtein. |
| |
| from __future__ import print_function |
| from bcc import BPF, USDT |
| from functools import partial |
| from time import sleep, strftime |
| import argparse |
| import re |
| import ctypes as ct |
| import os |
| import traceback |
| import sys |
| |
| class Probe(object): |
| probe_count = 0 |
| streq_index = 0 |
| max_events = None |
| event_count = 0 |
| first_ts = 0 |
| print_time = False |
| use_localtime = True |
| time_field = False |
| print_cpu = False |
| print_address = False |
| tgid = -1 |
| pid = -1 |
| page_cnt = None |
| |
| @classmethod |
| def configure(cls, args): |
| cls.max_events = args.max_events |
| cls.print_time = args.timestamp or args.time |
| cls.use_localtime = not args.timestamp |
| cls.time_field = cls.print_time and (not cls.use_localtime) |
| cls.print_cpu = args.print_cpu |
| cls.print_address = args.address |
| cls.first_ts = BPF.monotonic_time() |
| cls.tgid = args.tgid or -1 |
| cls.pid = args.pid or -1 |
| cls.page_cnt = args.buffer_pages |
| cls.bin_cmp = args.bin_cmp |
| |
| def __init__(self, probe, string_size, kernel_stack, user_stack): |
| self.usdt = None |
| self.streq_functions = "" |
| self.raw_probe = probe |
| self.string_size = string_size |
| self.kernel_stack = kernel_stack |
| self.user_stack = user_stack |
| Probe.probe_count += 1 |
| self._parse_probe() |
| self.probe_num = Probe.probe_count |
| self.probe_name = "probe_%s_%d" % \ |
| (self._display_function(), self.probe_num) |
| self.probe_name = re.sub(r'[^A-Za-z0-9_]', '_', |
| self.probe_name) |
| |
| # compiler can generate proper codes for function |
| # signatures with "syscall__" prefix |
| if self.is_syscall_kprobe: |
| self.probe_name = "syscall__" + self.probe_name[6:] |
| |
| def __str__(self): |
| return "%s:%s:%s FLT=%s ACT=%s/%s" % (self.probe_type, |
| self.library, self._display_function(), self.filter, |
| self.types, self.values) |
| |
| def is_default_action(self): |
| return self.python_format == "" |
| |
| def _bail(self, error): |
| raise ValueError("error in probe '%s': %s" % |
| (self.raw_probe, error)) |
| |
| def _parse_probe(self): |
| text = self.raw_probe |
| |
| # There might be a function signature preceding the actual |
| # filter/print part, or not. Find the probe specifier first -- |
| # it ends with either a space or an open paren ( for the |
| # function signature part. |
| # opt. signature |
| # probespec | rest |
| # --------- ---------- -- |
| (spec, sig, rest) = re.match(r'([^ \t\(]+)(\([^\(]*\))?(.*)', |
| text).groups() |
| |
| self._parse_spec(spec) |
| # Remove the parens |
| self.signature = sig[1:-1] if sig else None |
| if self.signature and self.probe_type in ['u', 't']: |
| self._bail("USDT and tracepoint probes can't have " + |
| "a function signature; use arg1, arg2, " + |
| "... instead") |
| |
| text = rest.lstrip() |
| # If we now have a (, wait for the balanced closing ) and that |
| # will be the predicate |
| self.filter = None |
| if len(text) > 0 and text[0] == "(": |
| balance = 1 |
| for i in range(1, len(text)): |
| if text[i] == "(": |
| balance += 1 |
| if text[i] == ")": |
| balance -= 1 |
| if balance == 0: |
| self._parse_filter(text[:i + 1]) |
| text = text[i + 1:] |
| break |
| if self.filter is None: |
| self._bail("unmatched end of predicate") |
| |
| if self.filter is None: |
| self.filter = "1" |
| |
| # The remainder of the text is the printf action |
| self._parse_action(text.lstrip()) |
| |
| def _parse_spec(self, spec): |
| parts = spec.split(":") |
| # Two special cases: 'func' means 'p::func', 'lib:func' means |
| # 'p:lib:func'. Other combinations need to provide an empty |
| # value between delimiters, e.g. 'r::func' for a kretprobe on |
| # the function func. |
| if len(parts) == 1: |
| parts = ["p", "", parts[0]] |
| elif len(parts) == 2: |
| parts = ["p", parts[0], parts[1]] |
| if len(parts[0]) == 0: |
| self.probe_type = "p" |
| elif parts[0] in ["p", "r", "t", "u"]: |
| self.probe_type = parts[0] |
| else: |
| self._bail("probe type must be '', 'p', 't', 'r', " + |
| "or 'u', but got '%s'" % parts[0]) |
| if self.probe_type == "t": |
| self.tp_category = parts[1] |
| self.tp_event = parts[2] |
| self.library = "" # kernel |
| self.function = "" # from TRACEPOINT_PROBE |
| elif self.probe_type == "u": |
| self.library = ':'.join(parts[1:-1]) |
| self.usdt_name = parts[-1] |
| self.function = "" # no function, just address |
| # We will discover the USDT provider by matching on |
| # the USDT name in the specified library |
| self._find_usdt_probe() |
| else: |
| self.library = ':'.join(parts[1:-1]) |
| self.function = parts[-1] |
| |
| # only x64 syscalls needs checking, no other syscall wrapper yet. |
| self.is_syscall_kprobe = False |
| if self.probe_type == "p" and len(self.library) == 0 and \ |
| self.function[:10] == "__x64_sys_": |
| self.is_syscall_kprobe = True |
| |
| def _find_usdt_probe(self): |
| target = Probe.pid if Probe.pid and Probe.pid != -1 \ |
| else Probe.tgid |
| self.usdt = USDT(path=self.library, pid=target) |
| for probe in self.usdt.enumerate_probes(): |
| if probe.name == self.usdt_name.encode('ascii'): |
| return # Found it, will enable later |
| self._bail("unrecognized USDT probe %s" % self.usdt_name) |
| |
| def _parse_filter(self, filt): |
| self.filter = self._rewrite_expr(filt) |
| |
| def _parse_types(self, fmt): |
| for match in re.finditer( |
| r'[^%]%(s|u|d|lu|llu|ld|lld|hu|hd|x|lx|llx|c|K|U)', fmt): |
| self.types.append(match.group(1)) |
| fmt = re.sub(r'([^%]%)(u|d|lu|llu|ld|lld|hu|hd)', r'\1d', fmt) |
| fmt = re.sub(r'([^%]%)(x|lx|llx)', r'\1x', fmt) |
| fmt = re.sub('%K|%U', '%s', fmt) |
| self.python_format = fmt.strip('"') |
| |
| def _parse_action(self, action): |
| self.values = [] |
| self.types = [] |
| self.python_format = "" |
| if len(action) == 0: |
| return |
| |
| action = action.strip() |
| match = re.search(r'(\".*?\"),?(.*)', action) |
| if match is None: |
| self._bail("expected format string in \"s") |
| |
| self.raw_format = match.group(1) |
| self._parse_types(self.raw_format) |
| for part in re.split('(?<!"),', match.group(2)): |
| part = self._rewrite_expr(part) |
| if len(part) > 0: |
| self.values.append(part) |
| |
| aliases_arg = { |
| "arg1": "PT_REGS_PARM1(ctx)", |
| "arg2": "PT_REGS_PARM2(ctx)", |
| "arg3": "PT_REGS_PARM3(ctx)", |
| "arg4": "PT_REGS_PARM4(ctx)", |
| "arg5": "PT_REGS_PARM5(ctx)", |
| "arg6": "PT_REGS_PARM6(ctx)", |
| } |
| |
| aliases_indarg = { |
| "arg1": "({u64 _val; struct pt_regs *_ctx = (struct pt_regs *)PT_REGS_PARM1(ctx);" |
| " bpf_probe_read(&_val, sizeof(_val), &(PT_REGS_PARM1(_ctx))); _val;})", |
| "arg2": "({u64 _val; struct pt_regs *_ctx = (struct pt_regs *)PT_REGS_PARM2(ctx);" |
| " bpf_probe_read(&_val, sizeof(_val), &(PT_REGS_PARM2(_ctx))); _val;})", |
| "arg3": "({u64 _val; struct pt_regs *_ctx = (struct pt_regs *)PT_REGS_PARM3(ctx);" |
| " bpf_probe_read(&_val, sizeof(_val), &(PT_REGS_PARM3(_ctx))); _val;})", |
| "arg4": "({u64 _val; struct pt_regs *_ctx = (struct pt_regs *)PT_REGS_PARM4(ctx);" |
| " bpf_probe_read(&_val, sizeof(_val), &(PT_REGS_PARM4(_ctx))); _val;})", |
| "arg5": "({u64 _val; struct pt_regs *_ctx = (struct pt_regs *)PT_REGS_PARM5(ctx);" |
| " bpf_probe_read(&_val, sizeof(_val), &(PT_REGS_PARM5(_ctx))); _val;})", |
| "arg6": "({u64 _val; struct pt_regs *_ctx = (struct pt_regs *)PT_REGS_PARM6(ctx);" |
| " bpf_probe_read(&_val, sizeof(_val), &(PT_REGS_PARM6(_ctx))); _val;})", |
| } |
| |
| aliases_common = { |
| "retval": "PT_REGS_RC(ctx)", |
| "$uid": "(unsigned)(bpf_get_current_uid_gid() & 0xffffffff)", |
| "$gid": "(unsigned)(bpf_get_current_uid_gid() >> 32)", |
| "$pid": "(unsigned)(bpf_get_current_pid_tgid() & 0xffffffff)", |
| "$tgid": "(unsigned)(bpf_get_current_pid_tgid() >> 32)", |
| "$cpu": "bpf_get_smp_processor_id()", |
| "$task" : "((struct task_struct *)bpf_get_current_task())" |
| } |
| |
| def _generate_streq_function(self, string): |
| fname = "streq_%d" % Probe.streq_index |
| Probe.streq_index += 1 |
| self.streq_functions += """ |
| static inline bool %s(char const *ignored, uintptr_t str) { |
| char needle[] = %s; |
| char haystack[sizeof(needle)]; |
| bpf_probe_read(&haystack, sizeof(haystack), (void *)str); |
| for (int i = 0; i < sizeof(needle) - 1; ++i) { |
| if (needle[i] != haystack[i]) { |
| return false; |
| } |
| } |
| return true; |
| } |
| """ % (fname, string) |
| return fname |
| |
| def _rewrite_expr(self, expr): |
| if self.is_syscall_kprobe: |
| for alias, replacement in Probe.aliases_indarg.items(): |
| expr = expr.replace(alias, replacement) |
| else: |
| for alias, replacement in Probe.aliases_arg.items(): |
| # For USDT probes, we replace argN values with the |
| # actual arguments for that probe obtained using |
| # bpf_readarg_N macros emitted at BPF construction. |
| if self.probe_type == "u": |
| continue |
| expr = expr.replace(alias, replacement) |
| for alias, replacement in Probe.aliases_common.items(): |
| expr = expr.replace(alias, replacement) |
| if self.bin_cmp: |
| STRCMP_RE = 'STRCMP\\(\"([^"]+)\\"' |
| else: |
| STRCMP_RE = 'STRCMP\\(("[^"]+\\")' |
| matches = re.finditer(STRCMP_RE, expr) |
| for match in matches: |
| string = match.group(1) |
| fname = self._generate_streq_function(string) |
| expr = expr.replace("STRCMP", fname, 1) |
| return expr |
| |
| p_type = {"u": ct.c_uint, "d": ct.c_int, "lu": ct.c_ulong, |
| "ld": ct.c_long, |
| "llu": ct.c_ulonglong, "lld": ct.c_longlong, |
| "hu": ct.c_ushort, "hd": ct.c_short, |
| "x": ct.c_uint, "lx": ct.c_ulong, "llx": ct.c_ulonglong, |
| "c": ct.c_ubyte, |
| "K": ct.c_ulonglong, "U": ct.c_ulonglong} |
| |
| def _generate_python_field_decl(self, idx, fields): |
| field_type = self.types[idx] |
| if field_type == "s": |
| ptype = ct.c_char * self.string_size |
| else: |
| ptype = Probe.p_type[field_type] |
| fields.append(("v%d" % idx, ptype)) |
| |
| def _generate_python_data_decl(self): |
| self.python_struct_name = "%s_%d_Data" % \ |
| (self._display_function(), self.probe_num) |
| fields = [] |
| if self.time_field: |
| fields.append(("timestamp_ns", ct.c_ulonglong)) |
| if self.print_cpu: |
| fields.append(("cpu", ct.c_int)) |
| fields.extend([ |
| ("tgid", ct.c_uint), |
| ("pid", ct.c_uint), |
| ("comm", ct.c_char * 16) # TASK_COMM_LEN |
| ]) |
| for i in range(0, len(self.types)): |
| self._generate_python_field_decl(i, fields) |
| if self.kernel_stack: |
| fields.append(("kernel_stack_id", ct.c_int)) |
| if self.user_stack: |
| fields.append(("user_stack_id", ct.c_int)) |
| return type(self.python_struct_name, (ct.Structure,), |
| dict(_fields_=fields)) |
| |
| c_type = {"u": "unsigned int", "d": "int", |
| "lu": "unsigned long", "ld": "long", |
| "llu": "unsigned long long", "lld": "long long", |
| "hu": "unsigned short", "hd": "short", |
| "x": "unsigned int", "lx": "unsigned long", |
| "llx": "unsigned long long", |
| "c": "char", "K": "unsigned long long", |
| "U": "unsigned long long"} |
| fmt_types = c_type.keys() |
| |
| def _generate_field_decl(self, idx): |
| field_type = self.types[idx] |
| if field_type == "s": |
| return "char v%d[%d];\n" % (idx, self.string_size) |
| if field_type in Probe.fmt_types: |
| return "%s v%d;\n" % (Probe.c_type[field_type], idx) |
| self._bail("unrecognized format specifier %s" % field_type) |
| |
| def _generate_data_decl(self): |
| # The BPF program will populate values into the struct |
| # according to the format string, and the Python program will |
| # construct the final display string. |
| self.events_name = "%s_events" % self.probe_name |
| self.struct_name = "%s_data_t" % self.probe_name |
| self.stacks_name = "%s_stacks" % self.probe_name |
| stack_table = "BPF_STACK_TRACE(%s, 1024);" % self.stacks_name \ |
| if (self.kernel_stack or self.user_stack) else "" |
| data_fields = "" |
| for i, field_type in enumerate(self.types): |
| data_fields += " " + \ |
| self._generate_field_decl(i) |
| time_str = "u64 timestamp_ns;" if self.time_field else "" |
| cpu_str = "int cpu;" if self.print_cpu else "" |
| kernel_stack_str = " int kernel_stack_id;" \ |
| if self.kernel_stack else "" |
| user_stack_str = " int user_stack_id;" \ |
| if self.user_stack else "" |
| |
| text = """ |
| struct %s |
| { |
| %s |
| %s |
| u32 tgid; |
| u32 pid; |
| char comm[TASK_COMM_LEN]; |
| %s |
| %s |
| %s |
| }; |
| |
| BPF_PERF_OUTPUT(%s); |
| %s |
| """ |
| return text % (self.struct_name, time_str, cpu_str, data_fields, |
| kernel_stack_str, user_stack_str, |
| self.events_name, stack_table) |
| |
| def _generate_field_assign(self, idx): |
| field_type = self.types[idx] |
| expr = self.values[idx].strip() |
| text = "" |
| if self.probe_type == "u" and expr[0:3] == "arg": |
| arg_index = int(expr[3]) |
| arg_ctype = self.usdt.get_probe_arg_ctype( |
| self.usdt_name, arg_index - 1) |
| text = (" %s %s = 0;\n" + |
| " bpf_usdt_readarg(%s, ctx, &%s);\n") \ |
| % (arg_ctype, expr, expr[3], expr) |
| |
| if field_type == "s": |
| return text + """ |
| if (%s != 0) { |
| void *__tmp = (void *)%s; |
| bpf_probe_read(&__data.v%d, sizeof(__data.v%d), __tmp); |
| } |
| """ % (expr, expr, idx, idx) |
| if field_type in Probe.fmt_types: |
| return text + " __data.v%d = (%s)%s;\n" % \ |
| (idx, Probe.c_type[field_type], expr) |
| self._bail("unrecognized field type %s" % field_type) |
| |
| def _generate_usdt_filter_read(self): |
| text = "" |
| if self.probe_type != "u": |
| return text |
| for arg, _ in Probe.aliases_arg.items(): |
| if not (arg in self.filter): |
| continue |
| arg_index = int(arg.replace("arg", "")) |
| arg_ctype = self.usdt.get_probe_arg_ctype( |
| self.usdt_name, arg_index - 1) |
| if not arg_ctype: |
| self._bail("Unable to determine type of {} " |
| "in the filter".format(arg)) |
| text += """ |
| {} {}_filter; |
| bpf_usdt_readarg({}, ctx, &{}_filter); |
| """.format(arg_ctype, arg, arg_index, arg) |
| self.filter = self.filter.replace( |
| arg, "{}_filter".format(arg)) |
| return text |
| |
| def generate_program(self, include_self): |
| data_decl = self._generate_data_decl() |
| if Probe.pid != -1: |
| pid_filter = """ |
| if (__pid != %d) { return 0; } |
| """ % Probe.pid |
| # uprobes can have a built-in tgid filter passed to |
| # attach_uprobe, hence the check here -- for kprobes, we |
| # need to do the tgid test by hand: |
| elif len(self.library) == 0 and Probe.tgid != -1: |
| pid_filter = """ |
| if (__tgid != %d) { return 0; } |
| """ % Probe.tgid |
| elif not include_self: |
| pid_filter = """ |
| if (__tgid == %d) { return 0; } |
| """ % os.getpid() |
| else: |
| pid_filter = "" |
| |
| prefix = "" |
| signature = "struct pt_regs *ctx" |
| if self.signature: |
| signature += ", " + self.signature |
| |
| data_fields = "" |
| for i, expr in enumerate(self.values): |
| data_fields += self._generate_field_assign(i) |
| |
| if self.probe_type == "t": |
| heading = "TRACEPOINT_PROBE(%s, %s)" % \ |
| (self.tp_category, self.tp_event) |
| ctx_name = "args" |
| else: |
| heading = "int %s(%s)" % (self.probe_name, signature) |
| ctx_name = "ctx" |
| |
| time_str = """ |
| __data.timestamp_ns = bpf_ktime_get_ns();""" if self.time_field else "" |
| cpu_str = """ |
| __data.cpu = bpf_get_smp_processor_id();""" if self.print_cpu else "" |
| stack_trace = "" |
| if self.user_stack: |
| stack_trace += """ |
| __data.user_stack_id = %s.get_stackid( |
| %s, BPF_F_REUSE_STACKID | BPF_F_USER_STACK |
| );""" % (self.stacks_name, ctx_name) |
| if self.kernel_stack: |
| stack_trace += """ |
| __data.kernel_stack_id = %s.get_stackid( |
| %s, BPF_F_REUSE_STACKID |
| );""" % (self.stacks_name, ctx_name) |
| |
| text = heading + """ |
| { |
| u64 __pid_tgid = bpf_get_current_pid_tgid(); |
| u32 __tgid = __pid_tgid >> 32; |
| u32 __pid = __pid_tgid; // implicit cast to u32 for bottom half |
| %s |
| %s |
| %s |
| if (!(%s)) return 0; |
| |
| struct %s __data = {0}; |
| %s |
| %s |
| __data.tgid = __tgid; |
| __data.pid = __pid; |
| bpf_get_current_comm(&__data.comm, sizeof(__data.comm)); |
| %s |
| %s |
| %s.perf_submit(%s, &__data, sizeof(__data)); |
| return 0; |
| } |
| """ |
| text = text % (pid_filter, prefix, |
| self._generate_usdt_filter_read(), self.filter, |
| self.struct_name, time_str, cpu_str, data_fields, |
| stack_trace, self.events_name, ctx_name) |
| |
| return self.streq_functions + data_decl + "\n" + text |
| |
| @classmethod |
| def _time_off_str(cls, timestamp_ns): |
| return "%.6f" % (1e-9 * (timestamp_ns - cls.first_ts)) |
| |
| def _display_function(self): |
| if self.probe_type == 'p' or self.probe_type == 'r': |
| return self.function |
| elif self.probe_type == 'u': |
| return self.usdt_name |
| else: # self.probe_type == 't' |
| return self.tp_event |
| |
| def print_stack(self, bpf, stack_id, tgid): |
| if stack_id < 0: |
| print(" %d" % stack_id) |
| return |
| |
| stack = list(bpf.get_table(self.stacks_name).walk(stack_id)) |
| for addr in stack: |
| print(" ", end="") |
| if Probe.print_address: |
| print("%16x " % addr, end="") |
| print("%s" % (bpf.sym(addr, tgid, |
| show_module=True, show_offset=True))) |
| |
| def _format_message(self, bpf, tgid, values): |
| # Replace each %K with kernel sym and %U with user sym in tgid |
| kernel_placeholders = [i for i, t in enumerate(self.types) |
| if t == 'K'] |
| user_placeholders = [i for i, t in enumerate(self.types) |
| if t == 'U'] |
| for kp in kernel_placeholders: |
| values[kp] = bpf.ksym(values[kp], show_offset=True) |
| for up in user_placeholders: |
| values[up] = bpf.sym(values[up], tgid, |
| show_module=True, show_offset=True) |
| return self.python_format % tuple(values) |
| |
| def print_event(self, bpf, cpu, data, size): |
| # Cast as the generated structure type and display |
| # according to the format string in the probe. |
| event = ct.cast(data, ct.POINTER(self.python_struct)).contents |
| values = map(lambda i: getattr(event, "v%d" % i), |
| range(0, len(self.values))) |
| msg = self._format_message(bpf, event.tgid, values) |
| if Probe.print_time: |
| time = strftime("%H:%M:%S") if Probe.use_localtime else \ |
| Probe._time_off_str(event.timestamp_ns) |
| print("%-8s " % time[:8], end="") |
| if Probe.print_cpu: |
| print("%-3s " % event.cpu, end="") |
| print("%-7d %-7d %-15s %-16s %s" % |
| (event.tgid, event.pid, |
| event.comm.decode('utf-8', 'replace'), |
| self._display_function(), msg)) |
| |
| if self.kernel_stack: |
| self.print_stack(bpf, event.kernel_stack_id, -1) |
| if self.user_stack: |
| self.print_stack(bpf, event.user_stack_id, event.tgid) |
| if self.user_stack or self.kernel_stack: |
| print("") |
| |
| Probe.event_count += 1 |
| if Probe.max_events is not None and \ |
| Probe.event_count >= Probe.max_events: |
| exit() |
| |
| def attach(self, bpf, verbose): |
| if len(self.library) == 0: |
| self._attach_k(bpf) |
| else: |
| self._attach_u(bpf) |
| self.python_struct = self._generate_python_data_decl() |
| callback = partial(self.print_event, bpf) |
| bpf[self.events_name].open_perf_buffer(callback, |
| page_cnt=self.page_cnt) |
| |
| def _attach_k(self, bpf): |
| if self.probe_type == "r": |
| bpf.attach_kretprobe(event=self.function, |
| fn_name=self.probe_name) |
| elif self.probe_type == "p": |
| bpf.attach_kprobe(event=self.function, |
| fn_name=self.probe_name) |
| # Note that tracepoints don't need an explicit attach |
| |
| def _attach_u(self, bpf): |
| libpath = BPF.find_library(self.library) |
| if libpath is None: |
| # This might be an executable (e.g. 'bash') |
| libpath = BPF.find_exe(self.library) |
| if libpath is None or len(libpath) == 0: |
| self._bail("unable to find library %s" % self.library) |
| |
| if self.probe_type == "u": |
| pass # Was already enabled by the BPF constructor |
| elif self.probe_type == "r": |
| bpf.attach_uretprobe(name=libpath, |
| sym=self.function, |
| fn_name=self.probe_name, |
| pid=Probe.tgid) |
| else: |
| bpf.attach_uprobe(name=libpath, |
| sym=self.function, |
| fn_name=self.probe_name, |
| pid=Probe.tgid) |
| |
| class Tool(object): |
| DEFAULT_PERF_BUFFER_PAGES = 64 |
| examples = """ |
| EXAMPLES: |
| |
| trace do_sys_open |
| Trace the open syscall and print a default trace message when entered |
| trace 'do_sys_open "%s", arg2' |
| Trace the open syscall and print the filename being opened |
| trace 'sys_read (arg3 > 20000) "read %d bytes", arg3' |
| Trace the read syscall and print a message for reads >20000 bytes |
| trace 'r::do_sys_open "%llx", retval' |
| Trace the return from the open syscall and print the return value |
| trace 'c:open (arg2 == 42) "%s %d", arg1, arg2' |
| Trace the open() call from libc only if the flags (arg2) argument is 42 |
| trace 'c:malloc "size = %d", arg1' |
| Trace malloc calls and print the size being allocated |
| trace 'p:c:write (arg1 == 1) "writing %d bytes to STDOUT", arg3' |
| Trace the write() call from libc to monitor writes to STDOUT |
| trace 'r::__kmalloc (retval == 0) "kmalloc failed!"' |
| Trace returns from __kmalloc which returned a null pointer |
| trace 'r:c:malloc (retval) "allocated = %x", retval' |
| Trace returns from malloc and print non-NULL allocated buffers |
| trace 't:block:block_rq_complete "sectors=%d", args->nr_sector' |
| Trace the block_rq_complete kernel tracepoint and print # of tx sectors |
| trace 'u:pthread:pthread_create (arg4 != 0)' |
| Trace the USDT probe pthread_create when its 4th argument is non-zero |
| trace 'p::SyS_nanosleep(struct timespec *ts) "sleep for %lld ns", ts->tv_nsec' |
| Trace the nanosleep syscall and print the sleep duration in ns |
| trace -I 'linux/fs.h' \\ |
| 'p::uprobe_register(struct inode *inode) "a_ops = %llx", inode->i_mapping->a_ops' |
| Trace the uprobe_register inode mapping ops, and the symbol can be found |
| in /proc/kallsyms |
| trace -I 'kernel/sched/sched.h' \\ |
| 'p::__account_cfs_rq_runtime(struct cfs_rq *cfs_rq) "%d", cfs_rq->runtime_remaining' |
| Trace the cfs scheduling runqueue remaining runtime. The struct cfs_rq is defined |
| in kernel/sched/sched.h which is in kernel source tree and not in kernel-devel |
| package. So this command needs to run at the kernel source tree root directory |
| so that the added header file can be found by the compiler. |
| trace -I 'net/sock.h' \\ |
| 'udpv6_sendmsg(struct sock *sk) (sk->sk_dport == 13568)' |
| Trace udpv6 sendmsg calls only if socket's destination port is equal |
| to 53 (DNS; 13568 in big endian order) |
| trace -I 'linux/fs_struct.h' 'mntns_install "users = %d", $task->fs->users' |
| Trace the number of users accessing the file system of the current task |
| """ |
| |
| def __init__(self): |
| parser = argparse.ArgumentParser(description="Attach to " + |
| "functions and print trace messages.", |
| formatter_class=argparse.RawDescriptionHelpFormatter, |
| epilog=Tool.examples) |
| parser.add_argument("-b", "--buffer-pages", type=int, |
| default=Tool.DEFAULT_PERF_BUFFER_PAGES, |
| help="number of pages to use for perf_events ring buffer " |
| "(default: %(default)d)") |
| # we'll refer to the userspace concepts of "pid" and "tid" by |
| # their kernel names -- tgid and pid -- inside the script |
| parser.add_argument("-p", "--pid", type=int, metavar="PID", |
| dest="tgid", help="id of the process to trace (optional)") |
| parser.add_argument("-L", "--tid", type=int, metavar="TID", |
| dest="pid", help="id of the thread to trace (optional)") |
| parser.add_argument("-v", "--verbose", action="store_true", |
| help="print resulting BPF program code before executing") |
| parser.add_argument("-Z", "--string-size", type=int, |
| default=80, help="maximum size to read from strings") |
| parser.add_argument("-S", "--include-self", |
| action="store_true", |
| help="do not filter trace's own pid from the trace") |
| parser.add_argument("-M", "--max-events", type=int, |
| help="number of events to print before quitting") |
| parser.add_argument("-t", "--timestamp", action="store_true", |
| help="print timestamp column (offset from trace start)") |
| parser.add_argument("-T", "--time", action="store_true", |
| help="print time column") |
| parser.add_argument("-C", "--print_cpu", action="store_true", |
| help="print CPU id") |
| parser.add_argument("-B", "--bin_cmp", action="store_true", |
| help="allow to use STRCMP with binary values") |
| parser.add_argument("-K", "--kernel-stack", |
| action="store_true", help="output kernel stack trace") |
| parser.add_argument("-U", "--user-stack", |
| action="store_true", help="output user stack trace") |
| parser.add_argument("-a", "--address", action="store_true", |
| help="print virtual address in stacks") |
| parser.add_argument(metavar="probe", dest="probes", nargs="+", |
| help="probe specifier (see examples)") |
| parser.add_argument("-I", "--include", action="append", |
| metavar="header", |
| help="additional header files to include in the BPF program " |
| "as either full path, " |
| "or relative to current working directory, " |
| "or relative to default kernel header search path") |
| parser.add_argument("--ebpf", action="store_true", |
| help=argparse.SUPPRESS) |
| self.args = parser.parse_args() |
| if self.args.tgid and self.args.pid: |
| parser.error("only one of -p and -L may be specified") |
| |
| def _create_probes(self): |
| Probe.configure(self.args) |
| self.probes = [] |
| for probe_spec in self.args.probes: |
| self.probes.append(Probe( |
| probe_spec, self.args.string_size, |
| self.args.kernel_stack, self.args.user_stack)) |
| |
| def _generate_program(self): |
| self.program = """ |
| #include <linux/ptrace.h> |
| #include <linux/sched.h> /* For TASK_COMM_LEN */ |
| |
| """ |
| for include in (self.args.include or []): |
| if include.startswith((".", "/")): |
| include = os.path.abspath(include) |
| self.program += "#include \"%s\"\n" % include |
| else: |
| self.program += "#include <%s>\n" % include |
| self.program += BPF.generate_auto_includes( |
| map(lambda p: p.raw_probe, self.probes)) |
| for probe in self.probes: |
| self.program += probe.generate_program( |
| self.args.include_self) |
| |
| if self.args.verbose or self.args.ebpf: |
| print(self.program) |
| if self.args.ebpf: |
| exit() |
| |
| def _attach_probes(self): |
| usdt_contexts = [] |
| for probe in self.probes: |
| if probe.usdt: |
| # USDT probes must be enabled before the BPF object |
| # is initialized, because that's where the actual |
| # uprobe is being attached. |
| probe.usdt.enable_probe( |
| probe.usdt_name, probe.probe_name) |
| if self.args.verbose: |
| print(probe.usdt.get_text()) |
| usdt_contexts.append(probe.usdt) |
| self.bpf = BPF(text=self.program, usdt_contexts=usdt_contexts) |
| for probe in self.probes: |
| if self.args.verbose: |
| print(probe) |
| probe.attach(self.bpf, self.args.verbose) |
| |
| def _main_loop(self): |
| all_probes_trivial = all(map(Probe.is_default_action, |
| self.probes)) |
| |
| # Print header |
| if self.args.timestamp or self.args.time: |
| print("%-8s " % "TIME", end=""); |
| if self.args.print_cpu: |
| print("%-3s " % "CPU", end=""); |
| print("%-7s %-7s %-15s %-16s %s" % |
| ("PID", "TID", "COMM", "FUNC", |
| "-" if not all_probes_trivial else "")) |
| |
| while True: |
| self.bpf.perf_buffer_poll() |
| |
| def run(self): |
| try: |
| self._create_probes() |
| self._generate_program() |
| self._attach_probes() |
| self._main_loop() |
| except: |
| exc_info = sys.exc_info() |
| sys_exit = exc_info[0] is SystemExit |
| if self.args.verbose: |
| traceback.print_exc() |
| elif not sys_exit: |
| print(exc_info[1]) |
| exit(0 if sys_exit else 1) |
| |
| if __name__ == "__main__": |
| Tool().run() |
