Add option to print virtual address to trace.py

man/man8/trace.8

@@ -3,7 +3,7 @@
 trace \- Trace a function and print its arguments or return value, optionally evaluating a filter. Uses Linux eBPF/bcc.
 .SH SYNOPSIS
 .B trace [-h] [-b BUFFER_PAGES] [-p PID] [-L TID] [-v] [-Z STRING_SIZE] [-S]
- [-M MAX_EVENTS] [-t] [-T] [-C] [-K] [-U] [-I header]
+ [-M MAX_EVENTS] [-t] [-T] [-C] [-K] [-U] [-a] [-I header]
  probe [probe ...]
 .SH DESCRIPTION
 trace probes functions you specify and displays trace messages if a particular
@@ -53,6 +53,8 @@ Print the kernel stack for each event.
 .TP
 \-U
 Print the user stack for each event.
+\-a
+Print virtual address in kernel and user stacks.
 .TP
 \-I header
 Additional header files to include in the BPF program. This is needed if your

tools/trace.py

@@ -4,7 +4,7 @@
 # parameters, with an optional filter.
 #
 # usage: trace [-h] [-p PID] [-L TID] [-v] [-Z STRING_SIZE] [-S]
-# [-M MAX_EVENTS] [-T] [-t] [-K] [-U] [-I header]
+# [-M MAX_EVENTS] [-T] [-t] [-K] [-U] [-a] [-I header]
 # probe [probe ...]
 #
 # Licensed under the Apache License, Version 2.0 (the "License")
@@ -31,6 +31,7 @@ class Probe(object):
  use_localtime = True
  time_field = False
  print_cpu = False
+ print_address = False
  tgid = -1
  pid = -1
  page_cnt = None
@@ -42,6 +43,7 @@ def configure(cls, args):
  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
@@ -474,13 +476,16 @@ def _display_function(self):
 
  def print_stack(self, bpf, stack_id, tgid):
  if stack_id < 0:
-  print(" %d" % stack_id)
-  return
+ print(" %d" % stack_id)
+ return
 
  stack = list(bpf.get_table(self.stacks_name).walk(stack_id))
  for addr in stack:
- print(" %s" % (bpf.sym(addr, tgid,
- show_module=True, show_offset=True)))
+ 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
@@ -645,6 +650,8 @@ def __init__(self):
  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",

tools/trace_example.txt

@@ -60,12 +60,25 @@ PID COMM FUNC -
 2740 bash readline man ls
 ^C
 
-The special retval keywords stands for the function's return value, and can
+The special retval keyword stands for the function's return value, and can
 be used only in a retprobe, specified by the 'r' prefix. The next component
 of the probe is the library that contains the desired function. It's OK to
 specify executables too, as long as they can be found in the PATH. Or, you
 can specify the full path to the executable (e.g. "/usr/bin/bash").
 
+Sometimes it can be useful to see where in code the events happen. There are
+flags to print the kernel stack (-K), the user stack (-U) and optionally
+include the virtual address in the stacks as well (-a):
+
+# trace.py -U -a 'r::sys_futex "%d", retval'
+PID TID COMM FUNC -
+793922 793951 poller sys_futex 0
+ 7f6c72b6497a __lll_unlock_wake+0x1a [libpthread-2.23.so]
+ 627fef folly::FunctionScheduler::run()+0x46f [router]
+ 7f6c7345f171 execute_native_thread_routine+0x21 [libstdc++.so.6.0.21]
+ 7f6c72b5b7a9 start_thread+0xd9 [libpthread-2.23.so]
+ 7f6c7223fa7d clone+0x6d [libc-2.23.so]
+
 Multiple probes can be combined on the same command line. For example, let's
 trace failed read and write calls on the libc level, and include a time column:
 
@@ -225,7 +238,7 @@ size and is measured in pages. The value must be a power of two and defaults to
 USAGE message:
 
 usage: trace [-h] [-b BUFFER_PAGES] [-p PID] [-L TID] [-v] [-Z STRING_SIZE]
- [-S] [-M MAX_EVENTS] [-t] [-T] [-K] [-U] [-I header]
+ [-S] [-M MAX_EVENTS] [-t] [-T] [-K] [-U] [-a] [-I header]
  probe [probe ...]
 
 Attach to functions and print trace messages.
@@ -251,6 +264,7 @@ optional arguments:
  -C, --print_cpu print CPU id 
  -K, --kernel-stack output kernel stack trace
  -U, --user-stack output user stack trace
+ -a, --address print virtual address in stacks
  -I header, --include header
  additional header files to include in the BPF program
  as either full path, or relative to current working directory,