1perf-probe(1)
2=============
3
4NAME
5----
6perf-probe - Define new dynamic tracepoints
7
8SYNOPSIS
9--------
10[verse]
11'perf probe' [options] --add='PROBE' [...]
12or
13'perf probe' [options] PROBE
14or
15'perf probe' [options] --del='[GROUP:]EVENT' [...]
16or
17'perf probe' --list
18or
19'perf probe' [options] --line='LINE'
20or
21'perf probe' [options] --vars='PROBEPOINT'
22
23DESCRIPTION
24-----------
25This command defines dynamic tracepoint events, by symbol and registers
26without debuginfo, or by C expressions (C line numbers, C function names,
27and C local variables) with debuginfo.
28
29
30OPTIONS
31-------
32-k::
33--vmlinux=PATH::
34	Specify vmlinux path which has debuginfo (Dwarf binary).
35
36-m::
37--module=MODNAME|PATH::
38	Specify module name in which perf-probe searches probe points
39	or lines. If a path of module file is passed, perf-probe
40	treat it as an offline module (this means you can add a probe on
41        a module which has not been loaded yet).
42
43-s::
44--source=PATH::
45	Specify path to kernel source.
46
47-v::
48--verbose::
49        Be more verbose (show parsed arguments, etc).
50
51-a::
52--add=::
53	Define a probe event (see PROBE SYNTAX for detail).
54
55-d::
56--del=::
57	Delete probe events. This accepts glob wildcards('*', '?') and character
58	classes(e.g. [a-z], [!A-Z]).
59
60-l::
61--list::
62	List up current probe events.
63
64-L::
65--line=::
66	Show source code lines which can be probed. This needs an argument
67	which specifies a range of the source code. (see LINE SYNTAX for detail)
68
69-V::
70--vars=::
71	Show available local variables at given probe point. The argument
72	syntax is same as PROBE SYNTAX, but NO ARGs.
73
74--externs::
75	(Only for --vars) Show external defined variables in addition to local
76	variables.
77
78-F::
79--funcs::
80	Show available functions in given module or kernel. With -x/--exec,
81	can also list functions in a user space executable / shared library.
82
83--filter=FILTER::
84	(Only for --vars and --funcs) Set filter. FILTER is a combination of glob
85	pattern, see FILTER PATTERN for detail.
86	Default FILTER is "!__k???tab_* & !__crc_*" for --vars, and "!_*"
87	for --funcs.
88	If several filters are specified, only the last filter is used.
89
90-f::
91--force::
92	Forcibly add events with existing name.
93
94-n::
95--dry-run::
96	Dry run. With this option, --add and --del doesn't execute actual
97	adding and removal operations.
98
99--max-probes::
100	Set the maximum number of probe points for an event. Default is 128.
101
102-x::
103--exec=PATH::
104	Specify path to the executable or shared library file for user
105	space tracing. Can also be used with --funcs option.
106
107In absence of -m/-x options, perf probe checks if the first argument after
108the options is an absolute path name. If its an absolute path, perf probe
109uses it as a target module/target user space binary to probe.
110
111PROBE SYNTAX
112------------
113Probe points are defined by following syntax.
114
115    1) Define event based on function name
116     [EVENT=]FUNC[@SRC][:RLN|+OFFS|%return|;PTN] [ARG ...]
117
118    2) Define event based on source file with line number
119     [EVENT=]SRC:ALN [ARG ...]
120
121    3) Define event based on source file with lazy pattern
122     [EVENT=]SRC;PTN [ARG ...]
123
124
125'EVENT' specifies the name of new event, if omitted, it will be set the name of the probed function. Currently, event group name is set as 'probe'.
126'FUNC' specifies a probed function name, and it may have one of the following options; '+OFFS' is the offset from function entry address in bytes, ':RLN' is the relative-line number from function entry line, and '%return' means that it probes function return. And ';PTN' means lazy matching pattern (see LAZY MATCHING). Note that ';PTN' must be the end of the probe point definition.  In addition, '@SRC' specifies a source file which has that function.
127It is also possible to specify a probe point by the source line number or lazy matching by using 'SRC:ALN' or 'SRC;PTN' syntax, where 'SRC' is the source file path, ':ALN' is the line number and ';PTN' is the lazy matching pattern.
128'ARG' specifies the arguments of this probe point, (see PROBE ARGUMENT).
129
130PROBE ARGUMENT
131--------------
132Each probe argument follows below syntax.
133
134 [NAME=]LOCALVAR|$retval|%REG|@SYMBOL[:TYPE]
135
136'NAME' specifies the name of this argument (optional). You can use the name of local variable, local data structure member (e.g. var->field, var.field2), local array with fixed index (e.g. array[1], var->array[0], var->pointer[2]), or kprobe-tracer argument format (e.g. $retval, %ax, etc). Note that the name of this argument will be set as the last member name if you specify a local data structure member (e.g. field2 for 'var->field1.field2'.)
137'TYPE' casts the type of this argument (optional). If omitted, perf probe automatically set the type based on debuginfo. You can specify 'string' type only for the local variable or structure member which is an array of or a pointer to 'char' or 'unsigned char' type.
138
139LINE SYNTAX
140-----------
141Line range is described by following syntax.
142
143 "FUNC[@SRC][:RLN[+NUM|-RLN2]]|SRC[:ALN[+NUM|-ALN2]]"
144
145FUNC specifies the function name of showing lines. 'RLN' is the start line
146number from function entry line, and 'RLN2' is the end line number. As same as
147probe syntax, 'SRC' means the source file path, 'ALN' is start line number,
148and 'ALN2' is end line number in the file. It is also possible to specify how
149many lines to show by using 'NUM'. Moreover, 'FUNC@SRC' combination is good
150for searching a specific function when several functions share same name.
151So, "source.c:100-120" shows lines between 100th to l20th in source.c file. And "func:10+20" shows 20 lines from 10th line of func function.
152
153LAZY MATCHING
154-------------
155 The lazy line matching is similar to glob matching but ignoring spaces in both of pattern and target. So this accepts wildcards('*', '?') and character classes(e.g. [a-z], [!A-Z]).
156
157e.g.
158 'a=*' can matches 'a=b', 'a = b', 'a == b' and so on.
159
160This provides some sort of flexibility and robustness to probe point definitions against minor code changes. For example, actual 10th line of schedule() can be moved easily by modifying schedule(), but the same line matching 'rq=cpu_rq*' may still exist in the function.)
161
162FILTER PATTERN
163--------------
164 The filter pattern is a glob matching pattern(s) to filter variables.
165 In addition, you can use "!" for specifying filter-out rule. You also can give several rules combined with "&" or "|", and fold those rules as one rule by using "(" ")".
166
167e.g.
168 With --filter "foo* | bar*", perf probe -V shows variables which start with "foo" or "bar".
169 With --filter "!foo* & *bar", perf probe -V shows variables which don't start with "foo" and end with "bar", like "fizzbar". But "foobar" is filtered out.
170
171EXAMPLES
172--------
173Display which lines in schedule() can be probed:
174
175 ./perf probe --line schedule
176
177Add a probe on schedule() function 12th line with recording cpu local variable:
178
179 ./perf probe schedule:12 cpu
180 or
181 ./perf probe --add='schedule:12 cpu'
182
183 this will add one or more probes which has the name start with "schedule".
184
185 Add probes on lines in schedule() function which calls update_rq_clock().
186
187 ./perf probe 'schedule;update_rq_clock*'
188 or
189 ./perf probe --add='schedule;update_rq_clock*'
190
191Delete all probes on schedule().
192
193 ./perf probe --del='schedule*'
194
195Add probes at zfree() function on /bin/zsh
196
197 ./perf probe -x /bin/zsh zfree or ./perf probe /bin/zsh zfree
198
199Add probes at malloc() function on libc
200
201 ./perf probe -x /lib/libc.so.6 malloc or ./perf probe /lib/libc.so.6 malloc
202
203SEE ALSO
204--------
205linkperf:perf-trace[1], linkperf:perf-record[1]
206